Synthetic methods for polyphenols

ABSTRACT

A process is disclosed for the production of polyphenol oligomers having n polyphenol monomeric units, n being an integer from 2-18. The process includes coupling of a protected polyphenol, having protected phenolic hydroxyl groups, with a C-4 functionalized polyphenol monomer. The protected polyphenol may be a protected polyphenol monomer or a protected polyphenol oligomer having 2-17 monomeric units. Advantageously, polyphenol monomeric units forming the polyphenol oligomers may be the same or different flavanoid compounds.

This application is a division of Ser. No. 10/017,812 filed on Dec. 14,2001, now U.S. Pat. No. 6,528,664, which is a continuation of Ser. No.09/169,554 filed on Oct. 9, 1998, now U.S. Pat. No. 6,420,572 issuedJul. 16, 2002, which is a continuation-in-part of Ser. No. 08/948,226filed on Oct. 9, 1997, now U.S. Pat. No. 6,207,842 issued on Mar. 27,2001.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to synthetic polyphenol monomers and oligomers,derivatives thereof, and methods for making and using the same.

2. Related Background Art

Polyphenols are a highly diverse group of compounds (Ferreira, D.,Steynberg, J. P., Roux, D. G. and Brandt, E. V., Tetrahedron, 48, (10),1743-1803 (1992)) which widely occur in a variety of plants, some ofwhich enter into the food chain. In many cases, they represent animportant class of compounds present in the human diet. Although some ofthe polyphenols are considered to be non-nutritive, interest in thesecompounds has arisen because of their possible beneficial effects onhealth.

For instance, quercetin (a flavonoid) has been shown to possessanticarcinogenic activity in experimental animal studies (Deschner, E.E., Ruperto, J., Wong, G. and Newmark, H. L., Carcinogenesis, 7,1193-1196 (1991) and Kato, R., Nakadate, T., Yamamoto, S. and Sugimura,T., Carcinogenesis, 4, 1301-1305 (1983)). (+)-Catechin and(−)-epicatechin (flavan-3-ols) have been shown to inhibit Leukemia virusreverse transcriptase activity (Chu S.-C., Hsieh, Y.-S. and Lim, J.-Y.,J. of Natural Products, 55, (2), 179-183 (1992)). Nobotanin (anoligomeric hydrolyzable tannin) has also been shown to possessanti-tumor activity (Okuda T., Yoshida, T., and Hatano, T., MolecularStructures and Pharmacological Activities of Polyphenols—OligomericHydrolyzable Tannins and Others—Presented at the XVIth InternationalConference of the Groupe Polyphenols, Lisbon, Portugal, Jul. 13-16,1992). Statistical reports have also shown that stomach cancer mortalityis significantly lower in the tea producing districts of Japan.Epigallocatechin gallate has been reported to be the pharmacologicallyactive material in green tea that inhibits mouse skin tumors (Okuda etal., ibid.). Ellagic acid has also been shown to possess anticarcinogenactivity in various animal tumor models (Boukharta M., Jalbert, G. andCastonguay, A., Efficacy of Ellagitannins and Ellagic Acid as CancerChemopreventive Agents—Presented at the XVIth International Conferenceof the Groupe Polyphenols, Lisbon, Portugal, Jul. 13-16, 1992).Proanthocyanidin oligomers have been disclosed (JP 4-190774) by theKikkoman Corporation for use as antimutagens. The use of phenoliccompounds in foods and their modulation of tumor development inexperimental animal models has been recently presented at the 202ndNational Meeting of The American Chemical Society (Phenolic Compounds inFoods and Their Effects on Health I, Analysis, Occurrence & Chemistry,Ho, C.-T., Lee, C. Y., and Huang, M.-T editors, ACS Symposium Series506, American Chemical Society, Washington, D.C. (1992); PhenolicCompounds in Foods and Their Effects on Health II. Antioxidants & CancerPrevention, Huang, M.-T., Ho, C.-T., and Lee, C. Y. editors, ACSSymposium Series 507, American Chemical Society, Washington, D.C.(1992)).

Procyanidin polyphenols, and particularly higher oligomers thereof, haverecently been found to possess a broad spectrum of biological activityReference is made to U.S. patent application Ser. No. 08/709,406 filedNov. 6, 1996, now U.S. Pat. No. 6,015,913 issued Jan. 18, 2000 and U.S.application Ser. No. 08/3 17,226 filed Oct. 3, 1994, now U.S. Pat. No.5,554,645 issued Sep. 10, 1996, each of which is incorporated herein byreference. These patents disclose a variety of health benefits providedby procyanidin polyphenols as well as a means of increasing theconcentration of these beneficial polyphenols in extracts, foods,pharmaceutical preparations and chocolate compositions. Reference isalso made to parent U.S. application Ser. No. 08/948,226 filed Oct. 9,1997, now U.S. Pat. No. 6,207,842 issued Mar. 27, 2001, which disclosesmethods of preparing polyphenol oligomers, and specifically procyanidinpolyphenols, the disclosure of which is also incorporated herein byreference.

Isolation, separation, purification, and identification methods havebeen established for the recovery of a range of procyanidin oligomersfor comparative in vitro and in vivo assessment of biologicalactivities. For instance, anti-cancer activity is elicited by pentamericthrough decameric procyanidins, but not by monomers through tetramericcompounds. Currently, gram quantities of pure (>95%) pentamer areobtained by time-consuming methods which are not satisfactory forobtaining a sufficient quantity of the pentamer for large scalepharmacological and bioavailability studies. Even greater effort isrequired to obtain gram quantities of higher oligomers, hexamers throughdodecamers, for similar studies since they are present in the naturalproduct in much lower concentrations than the pentamer. Additionally,increasing oligomeric size increases structural complexity. Factors suchas differences in the chirality of the monomeric units comprising theoligomer, different interflavan bonding sites, differences in thechirality of the interflavan bonding, dynamic rotational isomerizationof the interflavan bonds, and the multiple points of bonding atnucleophilic centers pose efficiency constraints on current analyticalmethods of separation and purification for subsequent identification.

These collective factors point to a need for synthesis methods to permitthe unambiguous proof of both structure and absolute configuration ofhigher oligomers, to provide large quantities of structurally definedoligomers for in vitro and in vivo assessment and to provide novelstructural derivatives of the naturally occurring procyanidins toestablish the structure-activity relationships of these materials.Accordingly, it would be advantageous to develop a versatile syntheticprocess capable of providing large quantities of any desired polyphenololigomer.

SUMMARY OF THE INVENTION

This invention is directed to a process for preparing a polyphenololigomer comprised of coupled polyphenol monomeric, or flavanoid, units.The process of this invention comprises:

-   -   (a) protecting each phenolic hydroxyl group of a polyphenol        monomer with a protecting group to form a protected polyphenol        monomer having the formula:        -   c is an integer from 1 to 3;        -   d is an integer from 1 to 4;        -   e is an integer from 0 to 2;        -   f is an integer from 0 to 2;        -   R¹ is H, OH or OR³;        -   R and R³ are independently protecting groups; and        -   R² is halo;    -   (b) functionalizing the 4-position of the protected polyphenol        monomer to form a functionalized, protected polyphenol monomer        having the formula;    -    wherein        -   c is an integer from 1 to 3;        -   d is an integer from 1 to 4;        -   e is an integer from 0 to 2;        -   f is an integer from 0 to 2;        -   y is an integer from 2 to 6;        -   R¹ is H, OH or OR³;        -   R⁴ is H or R⁵;        -   R, R³ and R⁵ are independently protecting groups; and        -   R² is halo;    -   (c) coupling the protected polyphenol monomer with the        functionalized protected polyphenol monomer to form a protected        polyphenol dimer, where the polyphenol monomeric units are the        same or different; and    -   (d) optionally repeating the functionalizing and coupling steps        to form a polyphenol oligomer having n monomeric units where n        is 3 to 18.

The process of this invention also provides for the preparation of novelderivatives of the polyphenol oligomer. Halogenation of thefunctionalized protected polyphenol monomer provides a halogenatedfunctionalized polyphenol monomer having the formula:

wherein, c is 1 to 3; d is 1 to 4; e is 1 or 2, f is 1 or 2; y is 2 to6; R′ is H, OH, or OR3; R⁴ is H or R⁵; R, R³ and R⁵ are independentlyprotecting groups; and R² is halo substituent which maybe the same ordifferent. This halogenated functionalized monomer may be used for theproduction of a halogenated polyphenol oligomer by coupling of thismonomer with either a protected polyphenol monomer or with a protectedpolyphenol oligomer. Alternatively, halogenated polyphenol oligomers maybe prepared by direct halogenation of the polyphenol oligomers.

Other novel derivatives may be prepared by esterifying or glycosylatingthe polyphenol oligomer to produce a derivatized polyphenol oligomer.Formation of the derivatized oligomers may be conducted either prior toor subsequent to removal of the protecting groups from the phenolichydroxyl groups of the polyphenol oligomer. Accordingly, this inventionis also directed to novel polyphenol monomers, novel polyphenololigomers, and novel derivatized polyphenol monomers and oligomers.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1(a) is a bar graph showing the dose-response relationship betweenthe control (solvent vehicle), monomer (epicatechin), pentamer (purifiedby preparative HPLC), ED “synthetic epicatechin dimer (EC-(4β→8)-EC)),and EDDG (synthesized epicatechin dimer bisgallate(EC-3-O-galloyl-(4β→8)-EC-3-O-gallate) against the human breast cancercell line MDA MB 231 at various μg/mL concentrations.

FIG. 1(b) is a bar graph showing the dose-response relationship betweenthe control (solvent vehicle), monomer (epicatechin), pentamer (purifiedby preparative HPLC), ED (synthetic epicatechin dimer (EC-(4β→8)-EC)),and EDDG (synthesized epicatechin dimer bisgallate(EC-3-O-galloyl-(4β→8)-EC-3-O-gallate)) against the human breast cancercell line MDA MB 435 at various μg/mL concentrations.

FIG. 1(c) is a bar graph showing the dose-response relationship betweenthe control (solvent vehicle), monomer (epicatechin), EGCG(epigallocatechin gallate from Sigma), ED (synthesized epicatechin dimer(EC-(4β→8)-EC)), EDDG (synthesized epicatechin dimer bisgallate(EC-3-O-galloyl-(4β→8)-EC-3-O-gallate)), ECDD (repeated synthesis ofepicatechin dimer bisgallate (EC-3-O-galloyl-(4β→8)-EC-3-O-gallate)),and ECTT (synthesized epicatechin trimer trisgallate([EC-3-O-galloyl-(4β→8)]₂-EC-3-O-gallate)) against the human breastcancer cell line MDA 231 at various μg/mL concentrations.

FIG. 1(d) is a bar graph showing the dose-response relationship betweenthe control (solvent vehicle), monomer (epicatechin), EGCG(epigallocatechin gallate from Sigma), ED (synthesized epicatechin dimer(EC-(4β→8)-EC)), EDDG (synthesized epicatechin dimer bisgallate(EC-3-O-galloyl-(4β→8)-EC-3-O-gallate)), ECDD (repeated synthesis ofepicatechin dimer bisgallate (EC-3-O-galloyl-(4β→8)-EC-3-O-gallate)),and ECTT (synthesized epicatechin trimer trisgallate([EC-3-O-galloyl(4β→8)]₂-EC-3-O-gallate)) against the human breastcancer cell line MCF-7 at various μg/mL concentrations.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a process of synthesizing polyphenololigomers and derivatives thereof. The subject compounds of theinvention have the same uses, and are formulated, purified andadministered in the same manner as described in U.S. Pat. No. 6,297,273issued Oct. 2, 2001. Accordingly, the compounds of this invention may beused, for example, as antineoplastic agents, antioxidants, DNAtopoisomerase II enzyme inhibitors, cyclo-oxygenase and/or lipoxygenasemodulators, nitric oxide or nitric oxide-synthase modulators, asnon-steroidal anti-flammatory agents, antimicrobial agents, apoptosismodulators, platelet aggregation modulators, glucose modulators, andinhibitors of oxidative DNA damage.

As used herein, the term polyphenol monomer means apolyhydroxy-substituted compound having the following flavanoid basedstructure:

wherein

-   -   c is an integer from 1 to 3;    -   d is an integer from 1 to 4;    -   R¹ is H or OH.

The polyphenol monomer may contain additional substituents, orderivatives of the hydroxyl substituents, as described below. The termpolyphenol oligomer means a polymer composed of a series of polyphenolmonomeric units that may possess the same or different flavanoidstructures. The polyphenol monomeric units are the polyphenol monomersthat have been coupled or bonded together to form an oligomer. The termpolyphenol(s) includes proanthocyanidins, and derivatives thereof, andspecifically includes procyanidins, such as those that can be extractedfrom cocoa beans, and derivatives thereof, as well as structurallysimilar synthetic materials.

Representative proanthocyanidins include:

Substitution Pattern Class Monomer 3 5 7 8 3′ 4′ 5′ ProapigeninidinApigeniflavan H OH OH H H OH H Proluteolinidin Luteoliflavan H OH OH HOH OH H Protricetinidin Tricetiflavan H OH OH H OH OH OH PropelargonidinAfzelechin OH OH OH H H OH H Procyanidin Catechin OH OH OH H OH OH HProdeiphinidin Gallocatechin OH OH OH H OH OH OH ProguibourtinidinGuibourtinidol OH H OH H H OH H Profisetinidin Fisetinidol OH H OH H OHOH H Prorobinetinidin Robinetinidol OH H OH H OH OH OH ProteracacinidinOritin OH H OH OH H OH H Promelacacinidin Prosopin OH H OH OH OH OH H

The present invention provides a process of preparing substantially purepolyphenol oligomers, and derivatives thereof.

In a preferred embodiment, the present invention provides a process ofsynthesizing polyphenol oligomers of the formula:

wherein

-   -   x is an integer from 0 to 16;    -   a is an integer from 1 to 15;    -   b is an integer from 1 to 15;    -   the sum a+b is an integer from 2 to 17;    -   c is independently an integer from 1 to 3;    -   d is independently an integer from 1 to 4;    -   e is independently an integer from 0 to 2;    -   f is independently an integer from 0 to 2;    -   R is independently hydrogen, C₁-C₄ alkyl, benzyl, substituted        benzyl, or a silyl moiety containing C₁-C₆ alkyl or aryl        substituents, or, when c or d is 2 and are adjacent, methylene,        diphenylmethylene or substituted diphenylmethylene, wherein said        substituted benzyl or each substituted phenyl may contain        substituents selected from the group consisting of halo, nitro,        cyano, aryl, C₁-C₆ alkyl, C₁-C₆ haloalkyl, C₁-C₆ alkoxy C₁-C₆        haloalkoxy, C₃-C₈ cycloalkyl, C₃-C₈ cycloalkoxy; and    -   R¹ is hydrogen, hydroxy, an —O-glycoside, an —O-substituted        glycoside, —OC(O)-aryl, —OC(O)-substituted aryl, —OC(O)-styryl,        or —OC(O)-substituted styryl; wherein the substituted glycoside        is substituted by —C(O)-aryl, —C(O)-substituted aryl,        —C(O)-styryl, or —C(O)-substituted styryl; wherein said        substituted aryl or substituted styryl may contain the        substituents selected from the group consisting of halo,        hydroxyl, nitro, cyano, aryl, amino, methylenedioxy, C₁-C₆        alkyl, C₁-C₆ alkoxy, C₁-C₆ haloalkyl, C₁-C₆ haloalkoxy, C₃-C₈        cycloalkyl, and C₃-C₈ cycloalkoxy;    -   R₂ is halo; and R² is halo, wherein if e+f is at least 2 the        halo substituent may be the same or different; and    -   wherein said process comprises the steps of subjecting a first        polyphenol monomer to conditions sufficient to produce a C-4        functionalized polyphenol monomer and coupling that C-4        functionalized monomer with a second polyphenol monomer or an        oligomer having up to 17 monomeric units that are the same or        different. The first and second polyphenol monomers may be the        same or different.

The process of the present invention may be used to preparesubstantially pure polyphenol oligomers, and derivatives thereof. Theoligomeric compounds are comprised of n polyphenol monomeric units,wherein n is an integer of 2 through 18, preferably 2 through 5, or 4through 12, more preferably n is 3 through 12, and most preferably n is5 through 12, and having linkages of 4→6 and 4→8. The polyphenololigomers prepared by the processes of this invention may be representedby the formula above, wherein x is 0 through 16, and higher. When x is0, the oligomer is termed a “dimer”; when x is 1, the oligomer is termeda “trimer”; when x is 2, the oligomer is termed a “trimer”; when x is 3,the oligomer is termed a “pentamer”; and similar recitations may bedesignated for oligomers having x up to and including 16 and higher,such that when x is 16, the oligomer is termed an “octadecamer”.

Linear and branched polyphenol oligomers may be prepared by the processof the present invention using a sequence of reaction comprisingprotecting, functionalizing, coupling, and deprotecting. In eachreaction sequence, any polyphenol monomer, as exemplified above, may beused to prepare linear or branched oligomers containing monomeric unitsof the same polyphenol monomer or of different polyphenol monomers.Higher oligomers may be prepared by repeating the coupling step bycoupling a dimer, trimer, or higher oligomer with additional monomer.

Generally, the process for the production of polyphenol oligomerscomprises the steps of:

-   -   (a) protecting each phenolic hydroxyl group of at least a first        and second polyphenol monomer using a suitable phenol protecting        group to provide at least a first and a second protected        polyphenol monomer, wherein the first and second polyphenol        monomers may be the same or different flavanoid compounds;    -   (b) functionalizing the 4-position of the first protected        polyphenol monomer to produce a functionalized polyphenol        monomer;    -   (c) coupling the functionalized polyphenol monomer with the        second protected polyphenol monomer to produce the polyphenol        oligomer, wherein the oligomer is a protected polyphenol dimer.

The polyphenol dimer thus produced is composed of the coupled first andsecond monomers, as the first functionalizing and second monomericunits. The functionalizing and coupling steps may be repeated to formpolyphenol oligomers, wherein the oligomers may be comprised of nmonomers, and n is an integer from 3 to 18. Preferably, n is an integerfrom 5-12.

Accordingly, the process described above may be continued by:

-   -   (a) functionalizing the 4-position of a third protected        polyphenol monomer to produce a third functionalized polyphenol        monomer;    -   (b) coupling the functionalized third polyphenol monomer with        the protected polyphenol dimer to produce a protected polyphenol        trimer;    -   (c) optionally repeating the functionalizing and coupling steps        to form a polyphenol oligomer comprised of n monomers, wherein n        is an integer from 4 to 18. The first, second and third        polyphenol monomers may possess the same or different flavanoid        structures.

Suitable protecting groups used in the process of this invention includethose protecting groups that may be introduced and removed from thepolyphenol monomers and oligomers without racemization or degradation ofthe monomers or oligomers and that are stable to the conditions used forfunctionalizing and coupling reactions. Methods for protecting andde-protecting hydroxyl groups are well known to those skilled in the artand are described in “Protective Groups in Organic Synthesis” T. W.Greene, John Wiley & Sons. Preferably, the protecting groups used in theprocess of this invention to protect the phenolic hydroxyl groups of thepolyphenol monomers include benzyl, C₁-C₄ alkyl, substituted benzyl,alkyl silyl, aryl silyl, or substituted aryl silyl containing C₁-C₆alkyl, aryl or substituted aryl substituents, wherein the substitutedbenzyl protecting group or substituted aryl may contain substituentsselected from the group consisting of halo, nitro, cyano, aryl, C₁-C₆alkyl, C₁-C₆ haloalkyl, C₁-C₆ alkoxy, C₁-C₆ haloalkoxy, C₃-C₈cycloalkyl, and C₃-C₈ cycloalkoxy. When the polyphenol monomer containstwo phenolic hydroxyl groups that are adjacent, the protecting group maybe methylene, diphenylmethylene or substituted diphenylmethylene,wherein each of the substituted phenyl groups of the diphenylmethyleneprotecting group may contain substituents selected from the groupconsisting of halo, nitro, cyano, aryl, C₁-C₆ alkyl, C₁-C₆ haloalkyl,C₁-C₆ alkoxy C₁-C₆ haloalkoxy, C₃-C₈ cycloalkyl, and C₃-C₈ cycloalkoxy.

As used herein, aryl means an aromatic hydrocarbon compound selectedfrom the group consisting of phenyl, substituted phenyl, naphthyl, orsubstituted naphthyl, wherein the substituted phenyl or substitutednaphthyl may contain substituents selected from the group consisting ofhalo, nitro, cyano, aryl, C₁-C₆ alkyl, C₁-C₆ haloalkyl, C₁-C₆ alkoxy,C₁-C₆ haloalkoxy, C₃-C₈ cycloalkyl, and C₃-C₈ cycloalkoxy.

The protecting group may be removed from the phenolic hydroxyl groups ofthe polyphenol oligomer to produce an unprotected polyphenol oligomer.In addition, the protected or unprotected polyphenol oligomer may bederivatized to produce derivatized polyphenol oligomers.

Preferably, the process of the present invention comprises:

-   -   (a) protecting each phenolic hydroxyl group of a first and        second polyphenol monomer using a suitable phenol protecting        group to provide a first and a second protected polyphenol        monomer, wherein the first and second polyphenol monomers may be        the same or different flavanoid compounds;    -   (b) oxidatively functionalizing the 4-position of the first        protected polyphenol monomer using an oxidizing agent to provide        a 4-functionalized protected polyphenol monomer;    -   (c) coupling the second protected polyphenol monomer and the        functionalized, protected polyphenol monomer using a catalyst to        provide a polyphenol dimer; and    -   (d) optionally deprotecting the polyphenol dimer to provide an        unprotected polyphenol dimer.

The oxidative functionalization of the 4-position of a protectedpolyphenol monomer produces a functionalized protected polyphenolmonomer having the formula:

wherein

-   -   c is an integer from 1 to 3;    -   d is an integer from 1 to 4;    -   e is an integer from 0 to 2;    -   f is an integer from 0 to 2;    -   y is an integer from 2 to 6;    -   R¹ is H, OH or OR³;    -   R⁴ is H or R⁵;    -   R, R³ and R⁵ are independently protecting groups; and    -   R² is halo.

When e or f are 1 or 2, functionalization of the monomer preferablyprecedes introduction of the halo substituent.

An important transformation in the process of the present invention isthe formation of the oxidatively functionalized protected polyphenolmonomer used in the oligomer-forming coupling reaction. It has beendetermined that high purity of this monomer is important for obtainingoligomeric products in good purity. Advantageously, it has beendiscovered that formation of the 4-alkoxy polyphenol monomer usingethylene glycol, in place of lower alkyl alcohols, provides afunctionalized polyphenol monomer that may be readily purified bychromatography. Use of methanol, ethanol, or even isopropyl alcohol,provides 4-alkoxy polyphenol monomers that are not separable ordifficult to separate chromatographically from the non-oxidized phenoland from by-products and cannot be used satisfactorily in theoligomer-forming coupling reaction. Accordingly, another aspect of thepresent invention comprises providing a substantially pure4(2-hydroxyethyl) functionalized polyphenol monomer useful for formingpolyphenol oligomers. A preferred quinone-type oxidizing agent is2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ).

Another important transformation in the process of this invention is thecoupling of the oxidatively functionalized polyphenol monomer to aprotected polyphenol monomer or a protected polyphenol oligomer. Thecoupling reaction is conducted using a protic acid catalyst or a Lewisacid catalyst. Hydrochloric acid (HCl) is an exemplary protic acid thatmay be used as a catalyst in the process of this invention. Aparticularly useful form of hydrochloric acid is as an anhydroussolution in dioxane. Exemplary Lewis Acid catalysts that are useful inthe present invention include titanium tetrahalides (e.g. titaniumtetrachloride), aluminum trihalides (e.g. aluminum trichloride), borontrihalides (e.g. boron trifluoride etherate), trialkyl or triaryl silylcompounds (e.g. trimethyl silyl triflate) and the like.

Exemplary oxidizing agents useful in the process of this inventioninclude quinone-type oxidizing agents and metal acetate oxidizing agents(e.g. lead tetraacetate).

Preferably, the process of the present invention comprises:

-   -   (a) protecting each phenolic hydroxyl group of a first and a        second polyphenol monomer using a benzyl ether protecting group        to produce a first and a second protected polyphenol monomer,        wherein the first and second polyphenol monomers may be the same        or different flavanoid compounds;    -   (b) oxidatively functionalizing the 4-position of the first        protected polyphenol monomer using a quinone oxidizing agent in        the presence of an alcohol, preferably a diol, to provide a        4-alkoxy functionalized protected polyphenol monomer having the        formula:    -    wherein        -   c is an integer from 1 to 3;        -   d is an integer from 1 to 4;        -   y is an integer from 2 to,6;        -   R is a protecting group; and        -   R¹ is H or OH;    -   (c) coupling the second protected polyphenol monomer and the        oxidatively functionalized, protected polyphenol monomer using a        protic acid catalyst or a Lewis acid catalyst to form a        protected polyphenol dimer; and    -   (d) deprotecting the protected polyphenol dimer to form an        unprotected polyphenol dimer.

More preferably, the process of the present invention comprises:

-   -   (a) protecting each phenolic hydroxyl group of a first and a        second polyphenol monomer using a benzyl ether protecting group        to produce a first and a second protected polyphenol monomer;    -   (b) oxidatively functionalizing the 4-position of the second        protected polyphenol monomer using        2,3-dichloro-5,6-dicyano-1,4-benzoquinone in the presence of        ethylene glycol to provide a 4-functionalized protected        polyphenol monomer having the formula:    -    wherein        -   c is an integer from 1 to 3;        -   d is an integer from 1 to 4;        -   R¹ is H or OH; and        -   Bz represents a benzyl moiety    -   (c) coupling the protected polyphenol monomer and the        functionalized, protected polyphenol monomer using titanium        tetrachloride to form a protected polyphenol dimer; and    -   (d) deprotecting the protected polyphenol dimer to form an        unprotected polyphenol dimer.

The processes of this invention also provides for the preparation ofnovel derivatized oligomers, wherein at least one unprotected hydroxylgroup of the polyphenol oligomer is derivatized using standardesterification or glycosylation techniques to form an ester or glycosylether derivative, respectively. Accordingly, this invention is directedto a process for the production of a derivatized polyphenol oligomer,which comprises esterifying a protected polyphenol oligomer, whereineach phenolic hydroxyl group of the polyphenol oligomer is protected, toproduce a protected esterified polyphenol oligomer, and to a processwhich comprises esterifying an unprotected polyphenol oligomer toproduce an esterified polyphenol oligomer. Optionally, the protectinggroups of the protected esterified polyphenol oligomer may be removed toprovide an esterified polyphenol oligomer. This invention is alsodirected to a process for the production of a derivatized polyphenololigomer, which comprises glycosylating the polyphenol oligomer, that isforming a glycosyl ether derivative of the oligomer, wherein eachphenolic hydroxyl group of the polyphenol oligomer is protected, toproduce a protected glycosylated polyphenol oligomer, and to a processwhich comprises glycosylating an unprotected polyphenol oligomer toproduce a glycosylated polyphenol oligomer. Optionally, the protectinggroups of the protected glycosylated polyphenol oligomer may be removedto provide a glycosylated polyphenol oligomer. In addition, esterderivatives of the glycosyl ethers may be prepared by esterifying atleast one hydroxyl group of the glycosyl moiety.

Polyphenol oligomer ester derivatives may be prepared by treatment ofthe oligomer having a reactive hydroxyl moiety with an activated acid.As used herein, an activated acid is an organic acid having a carboxylmoiety that is activated toward reaction with an hydroxyl moiety. Theactivated acid may be a compound that can be isolated, such as an acidchloride, an acid anhydride, a mixed acid anhydride and the like, or maybe formed in situ, for example by treatment of an acid with dicyclohexylcarbodiimide (DCC), carbonyl di-imidazole, and the like.

Polyphenol oligomer glycosides may be prepared by the methods describedin Toshima, K.,; Tatsuta, K. Chem. Rev., 93, 1503-1531 (1993), Igarashi,K. Adv. Carbobydr. Chem. Biochem., 34, 243 (1977) and D. Kahne et al.,J. Am. Chem. Soc., 11, 6881 (1989), or by treatment of a monomer usingcyclodextrin glucanotransferase (EC 2.4.1.19, CGTase) according to theprocedures described by Funayama et al. to produce a monomer glucoside(M. Funayama, H. Arakawa, R. Yamamoto, T. Nishino, T. Shin and S. Murao,Biosci. Biotech. Biochem., 58, (5), 817-821 (1994)).

According to the process of this invention, polyphenol oligomers,comprised of 2 to 18 monomeric units, may be esterified to provide anesterified polyphenol oligomer, wherein the 3-hydroxyl group on at leastone monomeric unit of the oligomer is converted to an ester, wherein theester moiety may be —OC(O)aryl, —OC(O)-substituted aryl, —OC(O)-styryl,—OC(O)-substituted styryl; wherein said substituted aryl or substitutedstyryl contains at least one substituent selected from the groupconsisting of halo, hydroxyl, nitro, cyano, amino, thiol,methylenedioxy, C₁-C₆ alkyl, C₁-C₆ alkoxy, C₁-C₆ haloalkyl, C₁-C₆haloalkoxy, C₃-C₈ cycloalkyl, and C₃-C₈ cycloalkoxy. Preferably, theester-moiety, —C(O)-substituted aryl and —C(O)-substituted styryl, isderived from an acid selected from the group consisting of caffeic,cinnamic, coumaric, ferulic, gallic, hydroxybenzoic and sinapic acids.

Additionally, polyphenol oligomers, comprised of 2 to 18 monomericunits, may be glycosylated to provide glycosylated polyphenol oligomers,wherein the 3-hydroxyl group on at least one monomeric unit of theoligomer is converted to a glycosyl ether, wherein the glycosyl moietymay be an —O-glycoside or an —O-substituted glycoside, wherein thesubstituted glycoside is substituted by —C(O)aryl, —C(O)-substitutedaryl, —C(O)-styryl, or —C(O)-substituted styryl; wherein saidsubstituted aryl or substituted styryl may contain the substituentsselected from the group consisting of halo, hydroxyl, nitro, cyano,amino, thiol, methylenedioxy, C₁-C₆ alkyl, C₁-C₆ alkoxy, C₁-C₆haloalkyl, C₁-C₆ haloalkoxy, C₃-C₈ cycloalkyl, and C₃-C₈ cycloalkoxy.Preferably, the glycoside moiety is derived from a sugar selected fromthe group consisting of glucose, galactose, xylose, rhamnose andarabinose.

Another embodiment of this invention provides a process for halogenatingthe protected polyphenol monomers, functionalized protected polyphenolmonomers and polyphenol oligomers prepared according the process of thisinvention. A halogenated polyphenol monomer having the formula:

wherein

-   -   c is an integer from 1 to 3;    -   d is an integer from 1 to 4;    -   e is an integer from 1 to 2;    -   f is an integer from 1 to 2;    -   R and R³ are independently a protecting group;    -   R¹ is H, OH, or OR³; and    -   R² is halo;        may be prepared by the process of treating a polyphenol monomer,        with a halogenating agent for a time and at a temperature        sufficient to effect the halogenation of the monomer. The halo        group may be chloro, bromo, fluoro, iodo or mixtures thereof.        The bromo group is most preferred. Exemplary halogenating agents        that may be useful in the process of this invention include,        N-bromosuccinimide, acetyl hypofluorite, cesium fluoroxysulfate,        trifluoromethyl hypofluorite, N-fluoropyridmium salts,        1-chloromethyl-4-fluoro-1,4 diazoniabicyclo[2.2.2]octaine        bis(tetrafluoroborate), sulfuryl chloride/diphenylsulfide (in        the presence of a Lewis Acid), sodium, calcium, or tert-butyl        hypochlorite, trimethyl(phenyl) ammonium tetrachloroiodate        (III), tetraethylammonium trichloride, iodine/periodic acid,        iodine/bis(trifluoroacetoxy)iodobenzene, iodine/copper (II)        acetate, iodine/silver sulfate, benzyl trimethylammonium        dichloroiodate(I) and the like. Other brominating agents of        catechins are described in Ballenegger et al., (Zyma SA)        European Patent 0096 007.

In yet another embodiment of this invention, a halogenatedfunctionalized polyphenol monomer having the formula:

wherein

-   -   c is an integer from 1 to 3;    -   d is an integer from 1 to 4;    -   e is an integer from 1 to 2;    -   f is an integer from 1 to 2;    -   y is an integer from 2 to 6;    -   R¹ is H, OH or R³;    -   R⁴ is H or R⁵;    -   R, R³ and R⁵ are independently protecting groups; and    -   R² is halo;        may be prepared by the process of treating a functionalized        polyphenol monomer, wherein e and f are 0, with a halogenating        agent for a time and at a temperature sufficient to effect the        halogenation of the monomer. The halo group(s) of R², when e+f        is at least 2, may be the same of different, i.e. selected from        the group consisting of chloro, fluoro, bromo, iodo.        Advantageously, different halogen substituents may be introduced        into the polyphenol monomer. For example, a polyphenol monomer        may be subjected to a first halogenation to introduce a halogen        substituent, so that for (R²)_(e), e is 1 and R₂ is bromo. This        halogenated monomer may then subjected to a second halogenation        to introduce a different halogen substituent, so that for        (R²)_(e), is 2 and R₂ is bromo and fluoro. Similarly,        halogenation may be conducted to introduce different halogen        substitutents at (R₂)_(f).

Alternatively, one or both of the alkoxy-hydroxyl groups of thefunctionalized polyphenol monomer may be protected with protectinggroups, R³ or R⁵, prior to halogenation, to provide a monomer having thefollowing formula:

Exemplary alcohol-hydroxyl protecting groups are the same protectinggroups (R), described above, that are useful for protecting the phenolichydroxyl moieties. The protecting group that may be used to protect thealcohol-hydroxyl moieties (R³ or R⁵) may be the same as or differentthan the protecting group used to protect the phenolic hydroxyl moieties(R). Preferably, the alcohol-hydroxyl moiety at the 3-position of thepolyphenol monomer may be protected using an alkyl silyl protectinggroup, preferably a tert-butyl-dimethylsilyl protecting group.Optionally, the alcohol-hydroxyl protecting groups(s) may be removedfrom the functionalized polyphenol monomer after halogenation or removedafter coupling to another monomer or oligomer. Most preferably, thealcohol-hydroxyl protecting group is selected such that removal of theprotecting group may be accomplished without removal of the halogensubstituent. For example, hydrogenolysis, used to remove benzylprotecting groups, of a benzylated-brominated monomer, will bothde-benzylate and de-brominate a monomer or an oligomer. The skilledartisan will recognize that the protecting group(s) and halogensubstitutent(s) may be selected such that these groups mayadvantageously be removed or retained during the protecting,halogenating, coupling, and deprotecting steps.

Limitation of the amount of halogenating agent used during thehalogenation reaction will provide for the selective formation of mono-,di-, tri- or tetra-halogenated polyphenol monomers. According to theprocess of this invention, use of approximately one equivalent ofhalogenating agent provides for the formation of mono-halogenatedmonomers, whereas use of 3 equivalents halogenating agent provides forthe preparation of tri-bromo protected polyphenol monomers and tri-bromofunctionalized protected polyphenol monomers.

The regiochemistry of the halogenation is dependent upon thesubstitution pattern of the starting polyphenol monomer, specifically,the hydroxyl-substitution pattern of the starting flavanoid monomer. Forexample, mono-bromination of protected polyphenol monomers, (+)-catechinor (−)-epicatechin, provides for the preparation of the 8-bromoderivatives of these flavanoids. Di-bromination of the protected(+)-catechin or (−)-epicatechin, provides for the preparation of6,8-dibromo products. Tri-bromination of the protected (+)-catechin or(−)-epicatechin, provides for the preparation of 6,8,6′-tribromoproducts. Accordingly, the process of this invention provides that anyand all of the polyphenol monomers or oligomers described herein, mayoptionally be subjected to halogenation to form novel halogenatedpolyphenol monomers or oligomers.

A mono-, di- or tri-halogenated, functionalized, protected polyphenolmonomer may be coupled with a protected polyphenol monomer or with aprotected polyphenol oligomer to produce a novel halogenated, protectedpolyphenol oligomer using any of the above described procedures.Coupling of the halogenated, functionalized, protected polyphenolmonomer with a halogenated, protected polyphenol monomer or with ahalogenated, protected polyphenol oligomer produces other novelhalogenated polyphenol oligomers. Coupling of the halogenated,functionalized monomer with an 8-halogenated, protected polyphenolmonomer or oligomer forms (4α→6) or (4β→6) coupled branched oligomers.Formation of these branched compounds maybe accomplished only when theprotecting groups on the phenolic hydroxyl groups of the halogenated,protected monomer or halogenated, protected oligomer do not preventreaction due to steric hinderance. For example, when sterically largeprotecting groups, such as benzyl, are present on the halogenated,protected polyphenol monomer, coupling will not occur. Whereas, couplingof unprotected polyphenols will provide branched oligomers. Preferably,the halogenated polyphenol oligomers produced herein are brominatedpolyphenol oligomers. Alternatively, halogenated polyphenol oligomersmay also be prepared by direct halogenation of a selected polyphenololigomer.

A further embodiment of this invention are derivatized or underivatizedhalogenated polyphenol monomers having the formula:

wherein

-   -   c is an integer from 1 to 3;    -   d is an integer from 1 to 4;    -   e is an integer from 0 to 2;    -   f is an integer from 0 to 2;        and        wherein    -   c is an integer from 1 to 3;    -   d is an integer from 1 to 4;    -   e is an integer from 1 to 2;    -   f is an integer from 1 to 2;    -   y is an integer from 2 to 6;        and, for each of the above.    -   R is C₁-C₄ alkyl, benzyl, substituted benzyl, C₁-C₄ alkyl, and a        silyl moiety containing C₁-C₆ alkyl or aryl substituents, or,        when c or d is 2 and are adjacent, methylene, diphenylmethylene        or substituted diphenylmethylene, wherein said substituted        benzyl or each substituted phenyl may contain substituents        selected from the group consisting of halo, nitro, cyano, aryl,        C₁-C₆ alkyl, C₁-C₆ haloalkyl, C₁-C₆ alkoxy C₁-C₆ haloalkoxy,        C₃-C₈ cycloalkyl, C₃-C₈ cycloalkoxy;    -   R¹ is hydrogen, hydroxy, an —O-glycoside, an —O-substituted        glycoside, —OC(O)-aryl, —OC(O)-substituted aryl, —OC(O)-styryl,        —OC(O)-substituted styryl; wherein the substituted glycoside is        substituted by —C(O)-aryl, —C(O)-substituted aryl, —C(O)-styryl,        —C(O)-substituted styryl; and    -   R² is halo;    -   wherein said substituted aryl or substituted styryl may contain        the substituents selected from the group consisting of halo,        hydroxyl, nitro, cyano, amino, thiol, methylenedioxy, C₁-C₆        alkyl, C₁-C₆ alkoxy, C₁-C₆ haloalkyl, C₁-C₆ haloalkoxy, C₃-C₈        cycloalkyl, and C₃-C₈ cycloalkoxy.

Accordingly, yet another embodiment of the invention is directed to aprocess for the production of a polyphenol oligomer by coupling ofpolyphenol monomers, wherein each phenolic hydroxyl group of thepolyphenol monomer is protected, comprising the steps of:

-   -   (a) functionalizing the 4-position of a first protected        polyphenol monomer to produce functionalized polyphenol monomer;    -   (b) blocking the 6- or 8-position of a protected polyphenol        monomer or oligomer to form a blocked, protected polyphenol        monomer or oligomer; and    -   (c) coupling the functionalized, protected polyphenol monomer or        oligomer with a blocked, protected polyphenol monomer or        oligomer to form a blocked protected polyphenol dimer or        oligomer.

Advantageously, the 8-position of the protected polyphenol is blockedsuch that the 4-position of the functionalized, protected polyphenolmonomer is coupled to the 6-position of the blocked, protectedpolyphenol.

The compounds prepared by the processes of this invention may bepurified, e.g., compounds or combinations thereof can be substantiallypure; for instance, purified to apparent homogeneity. Purity is arelative concept, and the numerous Examples demonstrate isolation ofcompounds or combinations thereof, as well as purification thereof, suchthat by methods exemplified a skilled artisan can obtain a substantiallypure compound or combination thereof, or purify them to apparenthomogeneity (e.g., purity by HPLC: observation of a singlechromatographic peak). As defined herein, a substantially pure compoundor combination of compounds is at least about 40% pure, e.g., at leastabout 50% pure, advantageously at least about 60% pure, e.g., at leastabout 70% pure, more advantageously at least about 75-80% pure,preferably, at least about 90% pure, more preferably greater than 90%pure, e.g., at least 90-95% pure, or even purer, such as greater than95% pure, e.g., 95-98% pure.

Moreover, stereoisomers of the oligomers are encompassed within thescope of the invention. The stereochemistry of the substituents on apolyphenol monomeric unit of the oligomer may be described in terms oftheir relative stereochemistry, “alpha/beta” or “cis/trans”, or in termsof absolute stereochemistry, “R/S”. The term “alpha” (α) indicates thatthe substituent is oriented below the plane of the flavan ring, whereas,“beta” (β) indicates that the substituent is oriented above the plane ofthe ring. The term “cis” indicates that two substituents are oriented onthe same face of the ring, whereas “trans” indicates that twosubstituents are oriented on opposite faces of the ring. The terms R andS are used to denote the arrangement of the substituents about astereogenic center, based on the ranking of the groups according to theatomic number of the atoms directly attached to that stereogenic center.For example, the flavanoid compound (+)-catechin, may be defined as(2R,trans)-2-(3′,4′-dihydroxyphenyl)-3,4-dihydro-2H-1-benzopyran-3,5,7-triol, or as (2R,3S)-flavan-3,3′,4′,5,7-pentaol. Interflavan(polyphenol monomeric unit-polyphenol monomeric unit) bonding is oftencharacterized using the relative terms α/β or cis/trans; α/β is usedherein to designate the relative stereochemistry of the interflavanbonding.

Linear and branched polyphenol oligomers may be prepared by the processof this invention. Any polyphenol monomer may be used to prepare linearor branched oligomers containing monomeric units having the same ordifferent flavanoid structures. The possible linkages between themonomeric units comprising the oligomers are distinguished by Top (T),Middle (M), Junction (J), and Bottom (B) linkages.

Representative examples for a linear pentamer and branched pentamer areshown below.

There are multiple stereochemical linkages, or bonding orientation,between position 4 of a monomeric unit and position 6 and 8 of theadjacent monomeric unit; the stereochemical linkages between monomericunits is designated herein as (4α→6) or (4β→6) or (4α→8) or (4β→8) forlinear oligomers. In addition to the stereochemical differences in theinterflavan bonding to carbon position 4, a bond to carbon position 2may have alpha or beta stereochemistry, and a bond to carbon position 3may have alpha or beta stereochemistry (e.g., (−)-epicatechin or(+)-catechin). For linkages to a branched or junction monomeric unit,the stereochemical linkages are (6→4α) or (6→4β) or (8→4α) or (8→4β).When one polyphenol monomeric unit (e.g., C or EC) is linked to anotherpolyphenol monomeric unit (e.g., EC or C), the linkages areadvantageously (4α→6) or (4α→8). Further regioisomers of the polyphenololigomers are encompassed within the scope of this invention. Oneskilled in the art will appreciate that rotation of a number of bondswithin the oligomer may be restricted due to steric hindrance,particularly if the oligomer is substituted, such as with benzyl groups.Accordingly, all possible regioisomers and stereoisomers of thecompounds of the invention are encompassed within the scope of theinvention.

In yet another embodiment, the invention is directed to a process forthe production of a desired regio- or stereoisomer of a polyphenololigomer of the formula:

wherein

-   -   x is an integer from 0 to 16;    -   c is independently an integer from 1 to 3;    -   d is independently an integer from 1 to 4;    -   R is independently C₁-C₄ alkyl, benzyl, substituted benzyl, and        a silyl moiety containing C₁-C₆ alkyl or aryl substituents, or,        when c or d is 2 and are adjacent, diphenylmethylene or        substituted diphenylmethylene, wherein said substituted benzyl        or each substituted phenyl may contain substituents selected        from the group consisting of halo, nitro, cyano, aryl, C₁-C₆        alkyl, C₁-C₆ haloalkyl, C₁-C₆ alkoxy C₁-C₆ haloalkoxy, C₃-C₈        cycloalkyl, C₃-C₈ cycloalkoxy; and    -   R¹ is an —O-glycoside, an —O-substituted glycoside, —OC(O)aryl,        —OC(O)-substituted aryl, —OC(O)-styryl, —OC(O)-substituted        styryl; wherein the substituted glycoside is substituted by        —C(—O)aryl, substituted —C(O)-aryl, —C(O)-styryl, substituted        —C(O)styryl; wherein said substituted aryl or substituted styryl        may contain the substituents selected from the group consisting        of halo, hydroxyl, nitro, cyano, amino, thiol, methylenedioxy,        C₁-C₆ alkyl, C₁-C₆ alkoxy, C₁-C₆ haloalkyl, C₁-C₆ haloalkoxy,        C₃-C₈ cycloalkyl, and C₃-C₈ cycloalkoxy; and wherein each        phenolic hydroxyl group of a polyphenol monomer is protected,        comprising the steps of:        -   (a) functionalizing the 4-position of a first polyphenol            monomer having a selected stereochemistry;        -   (b) coupling said functionalized polyphenol monomer with a            second polyphenol monomer having a selected stereochemistry            to form a dimer having a selected regiochemistry;        -   (c) purifying said dimer;        -   (d) if x is equal to 1, functionalizing the 4-position of a            third polyphenol monomer having a selected stereochemistry;        -   (e) coupling said functionalized third polyphenol monomer            having a selected stereochemistry with said dimer to form a            trimer having selected regiochemistry;        -   (f) purifying said trimer; and        -   (g) if x is greater than 1, sequentially adding            functionalized polyphenol monomer to said trimer and            successively higher oligomers by the steps recited above.

The invention is also directed to a process for producing a polyphenololigomer of the formula:

wherein

-   -   a bond to carbon position 2 has alpha or beta stereochemistry;    -   a bond to carbon position 3 has alpha or beta stereochemistry;    -   a bond to carbon position 4 has alpha or beta stereochemistry;        wherein:    -   c is independently an integer from 1 to 3;    -   d is independently an integer from 1 to 4;    -   x is 0 to 16;    -   R is independently C₁-C₄ alkyl, benzyl, substituted benzyl, and        a silyl moiety containing C₁-C₆ alkyl or aryl substituents, or,        when c or d is 2 and are adjacent, diphenylmethylene or        substituted diphenylmethylene, wherein said substituted benzyl        or each substituted phenyl may contain subsitutents selected        from the group consisting of halo, nitro, cyano, aryl, C₁-C₆        alkyl, C₁-C₆ haloalkyl, C₁-C₆ alkoxy C₁-C₆ haloalkoxy, C₃-C₈        cycloalkyl, C₃-C₈ cycloalkoxy; and    -   R¹ is hydroxy, an —O-glycoside, an —O-substituted glycoside,        —OC(O)-aryl, —OC(O)-substituted aryl, —OC(O)-styryl, or        —OC(O)-substituted styryl; wherein the substituted glycoside is        substituted by —C(O)-aryl, —C(O)-substituted aryl, —C(O)-styryl,        or —C(O)-substituted styryl; wherein said substituted aryl or        substituted styryl may contain the substituents selected from        the group consisting of halo, hydroxyl, nitro, cyano, amino,        thiol, methylenedioxy, C₁-C₆ alkyl, C₁-C₆ alkoxy, C₁-C₆        haloalkyl, C₁-C₆ haloalkoxy, C₃-C₈ cycloalkyl, and C₃-C₈        cycloalkoxy;        which comprises:    -   (a) reacting a protected polyphenol monomer of the formula:        wherein    -   m is an integer from 1 to 3;    -   n is an integer from 1 to 4; and    -   R is a protecting group selected from the group consisting of        C₁-C₄ alkyl, benzyl, substituted benzyl and a silyl moiety        containing C₁-C₆ alkyl or aryl substitutents, or, when c or d is        2 and are adjacent diphenylmethylene and substituted        diphenylmethylene a protecting group selected from the group        consisting of, wherein said substituted benzyl or each        substituted phenyl may contain substitutents selected from the        group consisting of halo, nitro, cyano, aryl, C₁-C₆ alkyl, C₁-C₆        haloalkyl, C₁-C₆ alkoxy C₁-C₆ haloalkoxy, C₃-C₈ cycloalkyl,        C₃-C₈ cycloalkoxy;    -   R¹ is H or OH;    -    with a protected phenolic monomer of the formula:    -    wherein        -   m is an integer from 1 to 3;        -   n is an integer from 1 to 4;        -   y is an integer from 2 to 6;        -   r is independently a protecting group selected from the            group consisting of C₁-C₄ alkyl benzyl, substituted benzyl,            and a silyl moiety containing C₁-C₆ alkyl or aryl            substituents, or, when c or d is 2 and are adjacent,            diphenylmethylene and substituted diphenylmethylene, wherein            said substituted benzyl or each substituted phenyl may            contain substituents selected from the group consisting of            halo, nitro, cyano, aryl, C₁-C₆ alkyl, C₁-C₆ haloalkyl,            C₁-C₆ alkoxy C₁-C₆ haloalkoxy, C₃-C₈ cycloalkyl, C₃-C₈            cycloalkoxy; and        -   R1 is H or OH;        -   to form a protected polyphenol dimer having protected            phenolic hydroxyl groups; and    -   (b) optionally deprotecting the phenolic hydroxyl groups of the        protected polyphenol dimer.

In a further embodiment, the invention is directed to a process for theproduction of a procyanidin polyphenol oligomer, which comprises:

-   -   (a) protecting each phenolic hydroxyl group of a (+)-catechin or        of a (−)-epicatechin with a protecting group to produce a        protected (+)-catechin or a protected (−)-epicatechin;    -   (b) functionalizing the 4-position of the protected (+)-catechin        or of the protected (−)-epicatechin to produce a functionalized        protected (+)-catechin or a functionalized protected        (−)-epicatechin having the formula:    -    wherein        -   y is an integer from 2 to 6;        -   R is a protecting group; and        -   R¹ is hydrogen, and    -   (c) coupling the protected (+)-catechin or the protected        (−)-epicatechin with the functionalized protected (+)-catechin        or the functionalized protected (−)-epicatechin to form a        protected polyphenol dimer.

In another embodiment, the invention is directed to a process ofpreparing a procyanidin polyphenol oligomer comprised of n monomericunits of (+)-catechin or (−)-epicatechin, wherein n is an integer from 2to 18, comprising:

-   -   (a) protecting each phenolic hydroxyl group of a (+)-catechin or        of a (−)-epicatechin with a suitable protecting group to produce        a protected (+)-catechin or a protected (−)epicatechin;    -   (b) functionalizing the 4-position of the protected (+)-catechin        or of the protected (−)-epicatechin to produce a functionalized        protected (+)-catechin or a functionalized protected        (−)-epicatechin having the formula:    -    wherein        -   y is an integer from 2 to 6;        -   R is a protecting group; and        -   R¹ is hydrogen; and    -   (c) coupling the protected (+)-catechin or the protected        (−)-epicatechin with the functionalized protected (+)-catechin        or the functionalized protected (−)-epicatechin to produce a        protected polyphenol oligomer, wherein n equals 2;    -   (d) removing the protecting group from each phenolic hydroxyl        group of the protected polyphenol oligomer to produce the        polyphenol oligomer, wherein n equals 2,    -   (e) coupling the protected polyphenol oligomer, wherein n equals        2, with a functionalized protected (+)-catechin or a        functionalized protected (−)-epicatechin monomer to produce a        protected polyphenol oligomer, wherein n equals 3,    -   (f) removing the protecting group from each phenolic hydroxyl        group of the protected polyphenol oligomer to produce the        polyphenol oligomer, wherein n equals 3,    -   (g) optionally repeating the process of coupling a protected        polyphenol oligomer, where n equals 3 or more, with a        functionalized protected (+)-catechin or a functionalized        protected (−)-epicatechin monomer to produce protected        polyphenol oligomers, wherein n equals 4to 18,    -   (h) removing the protecting group from each phenolic hydroxyl        group of the protected polyphenol oligomer to produce the        polyphenol oligomer, wherein n equals 4 to 18.

Advantageously, each phenolic hydroxyl group is protected using a benzylether protecting group, and y is 2.

In a further embodiment, the invention is directed to a process forproducing a procyanidin polyphenol oligomer of the formula:

wherein a bond to carbon position 2 has alpha or beta stereochemistry;

-   -   a bond to carbon position 3 has alpha or beta stereochemistry;    -   a bond to carbon position 4 has alpha or beta stereochemistry;    -   m is 0 to 16;    -   R is hydrogen; and    -   R¹ is hydrogen;        which comprises:    -   (a) reacting a compound selected from the group consisting of    -    or a mixture thereof, with a compound selected from the group        consisting of    -    or a mixture thereof,    -   wherein        -   y is an integer from 2 to 6; to form a protected polyphenol            oligomer having benzylated phenolic hydroxyl groups; and    -   (b) deprotecting the benzylated phenolic hydroxyl groups of the        protected polyphenol oligomer.

In a still further embodiment, the invention is directed to a processfor producing a polyphenol oligomer of the formula:

wherein a bond to carbon position 2 has alpha or beta stereochemistry;

-   -   a bond to carbon position 3 has alpha or beta stereochemistry;    -   a bond to carbon position 4 has alpha or beta stereochemistry;    -   m is 1 to 16;    -   R is hydrogen; and    -   R¹ is hydrogen;        which comprises:    -   (a) reacting a compound of the formula:    -    wherein a bond to carbon position 2 has alpha or beta        stereochemistry;        -   a bond to carbon position 3 has alpha or beta            stereochemistry;        -   a bond to carbon position 4 has alpha or beta            stereochemistry;        -   p is 0 to 15;        -   R is independently C₁-C₄ alkyl, benzyl, substituted benzyl,            and a silyl moiety containing C₁-C₆ alkyl or aryl            substituents, or, when c or d is 2 and are adjacent,            diphenylmethylene or substituted diphenylmethylene, wherein            said substituted benzyl or each substituted phenyl may            contain substituents selected from the group consisting of            halo, nitro, cyano, aryl, C₁-C₆ alkyl, C₁C₆ haloalkyl, C₁-C₆            alkoxy C₁-C₆ haloalkoxy, C₃-C₈ cycloalkyl, C₃-C₈            cycloalkoxy; and        -   R₁ is hydrogen, a glycoside, a substituted glycoside,            —C(O)-aryl, —C(O)-substituted aryl, —C(O)-styryl,            —C(O)-substituted styryl; wherein the substituted glycoside            is substituted by —C(O)aryl, —C(O)-substituted aryl,            —C(O)-styryl, —C(O)-substituted styryl; wherein said            substituted aryl or substituted styryl may contain the            substituents selected from the group consisting of halo,            hydroxyl, nitro, cyano, amino, thiol, methylenedioxy, C₁-C₆            alkyl, C₁-C₆ alkoxy, C₁-C₆ haloalkyl, C₁-C₆ haloalkoxy,            C₃-C₈ cycloalkyl, and C₃-C₈ cycloalkoxy; with a compound            selected from the group consisting of        -    or a mixture thereof,        -   wherein            -   m=p+1.

Flavanoid compounds, (+)-catechin and (−)-epicatechin, are used hereinto exemplify the types of polyphenol oligomers that may be prepared bythe process of this invention. The linkages between the adjacentpolyphenol monomeric units, (+)-catechin and (−)-epicatechin,abbreviated C and EC, respectively, are from position 4 to position 6 orposition 4 to position 8; and this linkage between position 4 of amonomer and position 6 and 8 of the adjacent monomeric units isdesignated herein as (4→6) or (4→8).

Examples of compounds within the scope of this invention include dimers,EC-(4β→8)-EC and EC-(4β→6)-EC, wherein EC-(4β→8)-EC is preferred;trimers [EC-(4β→8)]₂-EC, [EC-(4β→8)]₂-C and [EC-(4β→6)]₂-EC, wherein[EC-(4β→8)]₂-EC is preferred; tetramers [EC-(4β→8)]₃-EC, [EC-(4β→8)]₃-Cand [EC-(4β→8)]₂-EC(4β→6)-C, wherein [EC-(4β→8)]₃-EC is preferred; andpentamers [EC-(4β→8)]₄-EC, [EC-(4β→8)]₃-EC-(4β→6)-EC,[EC-(4β→8)]₃-EC(4β→8)-C and [EC-(4β→8)]₃-EC-(4β→6)-C, wherein[EC-(4β→8)]₄-EC is preferred. An example of a branched trimer is

examples of a branched tetramer include

an example of a branched pentamer is

Additionally, compounds which elicit the activities cited above alsoinclude hexamers to dodecamers, examples of which are listed below:

-   -   A hexamer, wherein one monomer (C or EC) is linked to a pentamer        compound listed above, e.g., [EC-(4β→8)]₅-EC,        [EC(4β→8)]₄-EC-(4β→6)-EC, [EC-(4β→8)]₄-EC-(4β→8)-C, and        [EC-(4β→8)]₄-EC-(4β→6)-C; wherein [EC-(4β→8)]₅-EC is preferred;        an example of a branched hexamer is    -   A heptamer, wherein any combination of two monomeric units (C        and/or EC) are linked to a pentamer compound listed above, e.g.,        [EC-(4β→8)]₆-EC, [EC-(4β→8)]₅-EC-(4β→6)-EC,        [EC-(4β→8)]₅-EC-(4β→8)-C, and [EC-(4β→8)]₅-EC-(4β→6)-C; in a        preferred embodiment, the heptamer is [EC-(4β→8)]₆-EC; an        example of a branched heptamer is    -   An octamer, wherein any combination of three monomeric units (C        and/or EC) are linked to a pentamer compound listed above, e.g.,        [EC-(4β→8)]₇-EC, [EC-(4β→8)]₆-EC-(4β→6)-EC,        [EC-(4β→8)]₆-EC(4β→8)-C, and [EC-(4β→8)]₆-EC-(4β→6)-C; in a        preferred embodiment, the octamer is [EC-(4β→8)]₇-EC; an example        of a branched octamer is    -   A nonamer, wherein any combination of four monomeric units (C        and/or EC) are linked to a pentamer compound listed above, e.g.,        [EC-(4β→8)]₈-EC, [EC-(4β→8)]₇-EC-(4β→6)-EC,        [EC-(4β→8)]₇-EC(4β→8)-C, and [EC-(4β→8)]₇-EC-(4β→6)-C; in a        preferred embodiment, the nonamer is [EC-(4β→8)]₈-EC; an example        of a branched nonamer is    -   A decamer, wherein any combination of five monomeric units (C        and/or EC) are linked to a pentamer compound listed above, e.g.,        [EC-(4β→8)]₉-EC, [EC-(4β→8)]₈-EC-(4β→6)-EC,        [EC-(4β→8)]8-EC(4β→8)-C, and [EC-(4β→8)]₈-EC-(4β→6)-C; in a        preferred embodiment, the decamer is [EC-(4β→8)]₉-EC; an example        of a branched decamer is    -   An undecamer, wherein any combination of six monomeric units (C        and/or EC) are linked to a pentamer compound listed above, e.g.,        [EC-(4β→8)]₁₀-EC, [EC-(4β→8)]₉-EC-(4β→6)-EC,        [EC-(4β→8)]₉-EC-(4β→8)-C, and [EC-(4β→8)]₉-EC-(4β→6)-C; in a        preferred embodiment, the undecamer is [EC-(4β→8)]₁₀-EC; an        example of a branched undecamer is    -   A dodecamer, wherein any combination of seven monomeric units (C        and/or EC) are linked to a pentamer compound listed above, e.g.,        [EC-(4β→8)]₁₁-EC, [EC-(4β→8)]₁₀-EC-(4β→6)-EC,        [EC-(4β→8)]₁₀-EC-(4β→8)-C, and [EC-(4β→8)]₁₀-EC-(4β→6)-C; in a        preferred embodiment, the dodecamer is [EC-(4β→8)]₁₁-EC; an        example of a branched

It will be understood from the detailed description that theaforementioned list is exemplary and is provided to illustrate the typesof compounds that may be prepared by the processes of this invention andis not intended as an exhaustive list of the compounds encompassed bythis invention.

The skilled artisan will recognize that the reaction sequence discussedabove may be modified at the final stages to yield oligomers havingx=2-16, without undue experimentation. Higher oligomers, i.e., x=2-16,can be isolated by employing the dimer and/or trimer as the startingmaterial for the coupling reaction, and the products derived therefrommay subsequently be used as starting material for coupling reactions toproduce even higher oligomers.

Moreover, the skilled artisan will recognize that various reagents maybe employed to practice the processes of this invention, without undueexperimentation, and without departing from the spirit or scope thereof.Skilled artisans will be able to envision additional routes ofsynthesis, based on this disclosure and the knowledge in the art,without undue experimentation, e.g, based upon a careful retrosyntheticanalysis of the polymeric compounds, as well as the monomers. Forexample, coupling of polyphenol monomers via an organometallicintermediate has been reported by K. Weinges et al. Chem. Ber. 103,2344-2349 (1970). In addition, linear and branched polyphenol oligomersmay be prepared by direct acid catalyzed coupling of monomericpolyphenol units, using conditions described by L. Y. Foo and R. W.Hemingway, J. Chem. Soc., Chem. Commun., 85-86 (1984); J. J. Botha, etal., J. Chem. Soc., Perkin I, 1235-1245 (1981); J. J. Botha et al.; J.Chem. Soc., Perkin I, 527-533 (1982), and H. Kolodziej, Phytochemistry25, 1209-1215 (1986).

Accordingly, yet another embodiment of this invention is directed to aprocess for the production of a desired regio- or stereoisomer of apolymeric compound of the formula A_(n), wherein A is a monomer of theformula:

wherein

-   -   n is an integer from 3 to 18, such that there is at least one        terminal monomeric unit A, and a plurality of additional        monomeric units;    -   R is 3-(α)-OH, 3-(β)-OH, 3-(α)-O-sugar, or 3-(β)-O-sugar;    -   bonding of adjacent monomers takes place between position 4 and        positions 6 or 8;    -   a bond for an additional monomeric unit in position 4 has alpha        or beta stereochemistry;    -   X, Y and Z are selected from the group consisting of monomeric        unit A, hydrogen, and a sugar, with the provisos that as to the        at least one terminal monomeric unit, bonding of the additional        monomeric unit thereto is at position 4 and optionally        Y=Z=hydrogen;    -   the sugar is optionally substituted with a phenolic moiety, and    -   pharmaceutically acceptable salts, derivatives thereof, and        oxidation products thereof;        which process comprises the steps of:    -   (a) functionalizing the 4-position of a first polyphenol        monomer;    -   (b) reacting said functionalized polyphenol monomer with a        second polyphenol monomer to form a dimer;    -   (c) purifying said dimer;    -   (d) functionalizing the 4-position of a third polyphenol        monomer;    -   (e) reacting said functionalized third polyphenol monomer with        said dimer to form a trimer;    -   (f) purifying said trimer;    -   (g) sequentially adding functionalized polyphenol monomer to        said trimer and successively higher oligomers by the steps        recited above; and    -   (h) optionally derivatizing the protected or unprotected        polyphenol oligomer to produce a derivatized polyphenol        oligomer.

Preferably, n is 5, the sugar is selected from the group consisting ofglucose, galactose, xylose, rhamnose and arabinose, and the phenolicmoiety is selected from the group consisting of caffeic, cinnamic,coumaric, ferulic, gallic, hydroxybenzoic and sinapic acids.

The invention is further directed to a process for the production of apolymeric compound of the formula A_(n), wherein A is a monomer of theformula:

wherein

-   -   n is an integer from 3 to 18, such that there is at least one        terminal monomeric unit A, and a plurality of additional        monomeric units;    -   R is 3-(α)-OH, 3-(β)-OH, 3-(α)-O-sugar, or 3-(β)-O-sugar;    -   bonding of adjacent monomers takes place between position 4 and        positions 6 or 8;    -   a bond for an additional monomeric unit in position 4 has alpha        or beta stereochemistry;    -   X, Y and Z are selected from the group consisting of monomeric        unit A, hydrogen, and a sugar, with the provisos that as to the        at least one terminal monomeric unit, bonding of the additional        monomeric unit thereto is at position 4 and optionally        Y═Z=hydrogen;    -   the sugar is optionally substituted with a phenolic moiety, and        pharmaceutically acceptable salts, derivatives thereof, and        oxidation products thereof;        which process comprises:    -   (a) protecting each phenolic hydroxyl group of a (+)-catechin or        of a (−)-epicatechin with a protecting group to produce a        protected (+)-catechin or a protected (−)-epicatechin;    -   (b) functionalizing the 4-position of the protected (+)-catechin        or of the protected (−)-epicatechin or of a mixture thereof to        produce a functionalized protected (+)catechin, a functionalized        protected (−)-epicatechin or a functionalized protected mixture        thereof;    -   (c) coupling a protected (+)-catechin or a protected        (−)-epicatechin with the functionalized    -   (d) removing the protecting group from the phenolic hydroxyl        groups of the polyphenol oligomer to produce an unprotected        polyphenol oligomer; and    -   (e) optionally derivatizing the protected or unprotected        polyphenol oligomer to produce a derivatized polyphenol        oligomer.

In still another embodiment, the invention is directed to a polymericcompound of the formula An, wherein A is a monomer of the formula:

wherein

-   -   n is an integer from 3 to 18, such that there is at least one        terminal monomeric unit A, and a plurality of additional        monomeric units;    -   R is 3-(α)-OH, 3-(β)-OH, 3-(α)-O-sugar, or 3-(β)-O-sugar;    -   bonding of adjacent monomers takes place between position 4 and        positions 6 or 8;    -   a bond for an additional monomeric unit in position 4 has alpha        or beta stereochemistry;    -   X, Y and Z are selected from the group consisting of monomeric        unit A, hydrogen, and a sugar, with the provisos that as to the        at least one terminal monomeric unit, bonding of the additional        monomeric unit thereto is at position 4 and optionally        Y=Z=hydrogen;    -   the sugar is optionally substituted with a phenolic moiety, and        pharmaceutically acceptable salts, derivatives thereof, and        oxidation products thereof.

Preferably, n is 5, the sugar is selected from the group consisting ofglucose, galactose, xylose, rhamnose and arabinose, and the phenolicmoiety is selected from the group consisting of caffeic, cinnamic,coumaric, ferulic, gallic, hydroxybenzoic and sinapic acids. Alsopreferably, the compound is substantially pure, preferably purified toapparent homogeneity.

Derivatives of the compound wherein one or more of the phenolic hydroxylgroups is benzylated are also encompassed within the scope of theinvention.

Adjacent monomers may bind at position 4 by (4→6) or (4→8); and each ofX, Y and Z is H, a sugar or an adjacent monomer, with the provisos thatif X and Y are adjacent monomers, Z is H or sugar and if X and Z areadjacent monomers, Y is H or sugar, and that as to at least one of thetwo terminal monomers, bonding of the adjacent monomer is at position 4and optionally, Y=Z=hydrogen.

One or more of the monomeric units may be derivatized with a gallate ora β-D-glucose, including the 3-position of a terminal monomeric unit.

These processes may be used to prepare linear or branched oligomerscontaining repeating monomeric units of a single polyphenol monomer orof different polyphenol monomers. Moreover, given the phenolic characterof the subject compounds, the skilled artisan can utilize variousmethods of phenolic coupling, selective protection/deprotection,organometallic additions, and photochemical reactions, e.g., in aconvergent, linear or biomimetic approach, or combinations thereof,together with standard reactions known to those well-versed in the artof synthetic organic chemistry, as additional synthetic methods forpreparing polyphenol oligomers. In this regard, reference is made to W.Carruthers, Some Modern Methods of Organic Synthesis, 3rd Ed., CambridgeUniversity Press, 1986, and J. March, Advanced Organic Chemistry, 3rdEd., John Wiley & Sons, 1985, van Rensburg et al., J. Chem. Soc. Chem.Commun. 24: 2705-2706 (Dec. 21, 1996), Ballenegger et al., (Zyma SA)European Patent 0096 007 B1, all of which are hereby incorporated hereinby reference.

The process of this invention also provides a means for incorporation ofan isotope label, e.g., deuterium and tritium, into polyphenololigomers. For example, a polyphenol monomer or oligomer may bedissolved in D₂O and CD₃CN, and gently heated in order to initiate H—Dexchange (this reaction can also be carried out using T₂O and CH₃CN inorder to incorporate a tritium into the molecule). Alternatively,deuterium or tritium may be incorporated using the methods of M. C.Pierre et al., Tetrahedron Letters 38, (32), 5639-5642 (1997) or E.Keihlmann et al., Can. J. Chem., 26, 2431-2439 (1988). The incorporationof a deuterium or tritium atom in the polyphenol oligomer facilitatesthe determination of how polyphenol compounds may be metabolizedfollowing ingestion.

This invention is also directed to a pharmaceutical compositioncomprising a compound of the formula:

and a pharmaceutically acceptable carrier or excipient, and to a methodfor treating a subject in need of treatment with an anticancer agentcomprising administering to the subject an effective amount of thecomposition. The cancer includes breast cancer.

In still yet another embodiment, the invention is directed to apharmaceutical composition comprising a compound of the formula:

and a pharmaceutically acceptable carrier or excipient, and to a methodfor treating a subject in need of treatment with an anticancer agentcomprising administering to the subject an effective amount of thecomposition. The cancer includes breast cancer.

Examples 8 and 10 describe the preparation of a dimer bisgallate andtrimer trisgallate, respectively. Their in vitro assessment (Example 25against several human breast cancer cell lines showed activityequivalent to the pentamer. These results were surprising, sincegallation of previously inactive procyanidin dimer and trimersubstantially increased the antineoplastic activity of these oligomers.

Table: Gallated Procyanidin Oligomers

-   EC-3-O-galloyl-(4β→8)-EC-3-O-gallate-   C-3-O-galloyl-(4α→8)-EC-3-O-gallate-   C-3-O-galloyl-(4α-8)-C-   EC-(4β→8)-EC-3-O-gallate-   C-(4α→8)-EC-3-O-gallate-   EC-3-O-galloyl-(4β→8)-C-   EC (4β→8)-EC-3-O-β-D-glucose-4,6-bisgallate-   [EC-3-O-galloyl-(4β→8)]₂-EC-3-O-gallate-   [EC-3-O-galloyl-(4β→8)]₃-EC-3-O-gallate-   [EC-(4β→8)]₄-EC-3-O-gallate-   [EC-(4β→8)]₅-EC-3-O-gallate-   [EC-(4β→8)]₆-EC-3-O-gallate-   [EC-(4β→8)]₇-EC-3-O-gallate-   [EC-(4β→8)]₈-EC-3-O-gallate-   [EC-(4β→8)]₉-EC-3-O-gallate-   [EC-(4β→8)]₁₀-EC-3-O-gallate-   [EC-(4β→8)]₁₁-EC-3-O-gallate

The Examples which follow are intended as an illustration of certainpreferred embodiments of the invention, and no limitation of theinvention is implied. The skilled artisan will recognize many variationsin these examples to cover a wide range of formulas and processing torationally adjust the compounds of the invention for a variety ofapplications without departing from the spirit or scope of theinvention.

In the following examples, (+)-catechin and (−)-epicatechin areexemplary polyphenol monomers used to demonstrate the processes of thepresent invention and no limitation of the invention is implied. The(−)-epicatechin as used herein, may be obtained from commercial sources,or protected epicatechin may be prepared from protected (+)-catechin(Example 3).

EXAMPLE 1 Preparation of (2R,3S, trans)-5,7,3′,4′-Tetra-O-benzylcatechin

A solution of (+)-catechin (65.8 g, 226.7 mmol, anhydrous), dissolved inanhydrous dimethylformamide (DMF, 720 mL), was added dropwise, at roomtemperature over a period of 80 min, to a stirred suspension of sodiumhydride, 60% in oil, (39 g, 975 mmol, 4.3 eq.) in DMF (180 mL). (S.Miura, et al., Radioisotopes, 32, 225-230 (1983)) After stirring for 50min, the flask was placed in a −10° C. NaCl/ice bath. Benzyl bromide(121 mL, 1.02 mol, 4.5 eq.) was added dropwise within 80 min. and thebrown reaction mixture warmed to room temperature, with stirring,overnight. The resulting reaction mixture was evaporated and theresulting candy-like solid was dissolved, with heating and stirring, intwo portions of solvent each consisting of 200 mL of chloroform (CHCl₃)and 100 mL of water. The phases were separated, the aqueous phaseextracted with CHCl₃ (20 mL), and the combined organic phases washedwith water (100 mL), dried over magnesium sulfate (MgSO₄) andevaporated. The residue was purified by chromatography on silica gel(42×10 cm; ethyl acetate/chloroform/hexane 1:12:7) to provide, afterevaporation and drying in vacuo, 85 g crude product, which wasrecrystallized from trichloroethylene (1.3 L) to provide 35.1 g (24%) ofan off-white powder. ¹H NMR (CDCl₃) δ 7.47-7.25 (m, 20H), 7.03 (s, 1H),6.95 (s, 2H), 6.27, 6.21 (ABq, 2H, J=2 Hz), 5.18 (s, 2H), 5.17 (narrowABq, 2H), 5.03 (s, 2H), 4.99 (s, 2H), 4.63 (d, 1H, J=8.5 Hz), 4.00 (m,1H), 3.11, 2.65 (ABq, 2H, J=16.5 Hz, both parts d with J=5.5 and 9 Hz,resp.), 1.59 (d, 1H, J=3.5 Hz); IR (film) 3440 (br), 1618, 1593, 1513,1499, 1144, 1116, 733, 696 cm⁻¹; MS m/z 650 (M+, 0.5%), 319, 181, 91.

Alternatively, the tetra-O-benzyl (+)-catechin may be prepared using themethod described by H. Kawamoto et al, Mokazai Gakkaishi, 37, (5)488-493 (1991), using potassium carbonate and benzyl bromide in DMF.Partial racemization of catechin, at both the 2- and 3-positions, wasobserved by M.-C. Pierre et al., Tetrahedron Letters, 38, (32) 5639-5642(1997).

EXAMPLE 2 Preparation of (2R)-5,7,3′,4′ Tetrakis(benzyloxy)flavan-3-one

Freshly prepared Dess-Martin periodinane (39.0 g, 92 mmol, prepared bythe method of D. B. Dess and J. C. Martin, J. Am. Chem. Soc. 113,7277-7287 (1991) and R. E. Ireland and L. Liu, J. Org. Chem. 58, 2899(1993)), was added at room temperature, all at once, to a stirredsolution of the tetra-O-benzylcatechin according to Example 1 (54.4 g,83.8 mmol) in methylene chloride (420 mL). Within 1.5 h, approx. 30 mLof water-saturated methylene chloride was added dropwise to the reactionmixture to form a turbid amber-colored solution. (S. D. Meyer and S. L.Schreiber, J. Org. Chem., 59, 7549-7552 (1994)) Twenty minutesthereafter, the reaction mixture was diluted with a saturated solutionof sodium carbonate (NaHCO₃, 500 mL) and a 10% aqueous solution ofNa₂S₂O₃.5H₂O (200 mL). The phases were separated and the aqueous phaseextracted with 50 mL of methylene chloride. The combined organic phaseswere filtered over silica gel (24×9 cm, chloroform/ethyl acetate 9:1).The eluate was evaporated and dried in vacuo to obtain 50.1 g (92%) ofthe ketone, which was purified by recrystallization fromchloroform/ether: mp 144-144.5° C.; [α]_(D)+38.5°, [α]₅₄₆+48.7°(chloroform, c 20.8 g/L); ¹H NMR (CDCl₃) δ 7.45-7.26 (m, 20H), 6.96 (s,1H), 6.88, 6,86 (ABq, 2H, J=8 Hz, B part d with J=1.5 Hz), 6.35 (narrowABq, 2H), 5.24 (s, 1H), 5.14 (s, 2H), 5.10 (narrow ABq, 2H), 5.02 (s,2H), 5.01 (s, 2H), 3.61, 3.45 (ABq, 2H, J=21.5 Hz).

EXAMPLE 3 Preparation of 5,7,3′,4′-Tetra-O-benzylepicatechin

A 1 M solution of lithium tri-sec-butylborohydride in tetrahydrofuran,herein after THF, (100 mL, L-Selectride®, sold by the Aldrich ChemicalCo, Inc., Milwaukee, Wis.) was added, under an argon atmosphere, to astirred, 0° C. solution of anhydrous lithium bromide, LiBr, (34.9 g, 402mmol) in 100 mL anhydrous THF. The resulting mixture was cooled to −78°C., using an acetone/CO₂ bath, followed by dropwise addition of asolution of the flavanone according to Example 2 (50.1 g, 77.2 mmol) in400 mL of anhydrous THF, over a period of 50 min. Stirring was continuedat −78° C. for 135 min. The cooling bath was removed and 360 mL of 2.5 Maqueous sodium hydroxide (NaOH) was added to the reaction mixture. Thereaction flask was placed in a room temperature water bath and a mixtureof 35% aqueous H₂O₂ (90 mL) and ethanol (270 mL) was added over a periodof 130 min. Stirring was continued overnight. Chloroform (700 mL) wasadded to dissolve the crystallized product, the phases were separated,the aqueous phase was extracted with CHCl₃ (50 mL), the combined organicphases were dried over MgSO₄, evaporated and dried in vacuo to provide56.6 g of crude product. This material was dissolved in 600 mL of aboiling mixture of ethyl acetate (EtOAc) and ethanol (EtOH), (2:3), andallowed to crystallize at room temperature, then in the refrigerator.The product was isolated by suction filtration, washed with 2×50 mL ofcold (−20° C.) EtOAc/EtOH (1:3), and dried in vacuo first at roomtemperature, then at 80° C. to obtain 35.4 g (70%) of a light yellowsolid. The evaporated mother liquor was filtered over silica gel, SiO₂,(14×6.5 cm, CHCl₃, then CHCl₃/EtOAc 12:1), the eluate concentrated to 40mL, and the residue diluted with 60 mL of ethanol, to obtain anadditional 5.5 g (11%) of the O-benzylepicatechin as a yellowish solid:mp 129.5-130° C. (from EtOAc/EtOH); [α]_(D)−27.7°, [α]₅₄₆−33.4° (EtOAc,c 21.6 g/L); ¹H NMR (CDCl₃) δ 7.48-7.25 (m, 20H), 7.14 (s, 1H), 7.00,6.97 (ABq, 2H, J=8.5 Hz, A part d with J=1.5 Hz), 6.27 (s, 2H), 5.19 (s,2H), 5.18 (s, 2H), 5.02 (s, 2H), 5.01 (s, 2H), 4.91 (s, 1H), 4.21 (br s,1H), 3.00, 2.92 (ABq, 2H, J=17.5 Hz, both parts d with J=1.5 and 4 Hz,resp.), 1.66 (d, 1H, J=5.5 Hz); Anal. Calcd. for C₄₃H₃₈O₆: C, 79.36; H,5.89. Found: C, 79.12: H, 5.99.

EXAMPLE 4 Preparation of (2R,3S,4S)-5,7,3′,4′-TetraO-benzyl-4-(2-hydroxyethoxy)epicatechin

Ethylene glycol (6.4 mL, 115 mmol, 5.8 eq.) was added, at roomtemperature, with stirring, to a solution of thetetra-O-benzylepicatechin according to Example 3 (12.75 g, 19.6 mmol) in130 mL of anhydrous methylene chloride, followed by addition of2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ, 8.9 g, 39.2 mmol, 2.0eq.), at one time, with vigorous stirring. (J. A. Steenkamp, et al.,Tetrahedron Letters, 26, (25) 3045-3048 (1985)). After approximately 2hours, 4-dimethylaminopyridine (DMAP, 4.8 g, 39.2 mmol) was added to thereaction mixture, resulting in the formation of a dark greenprecipitate. After stirring for an additional 5 minutes, 100 g of silicagel was added, and the mixture was concentrated under reduced pressure.The residue was placed on top of a silica gel column (11×6.5 cm) whichwas eluted with EtOAc/hexane (1:1), and the eluate was concentratedunder reduced pressure. The resulting crude material was re-purified bychromatography on silica gel (39×10 cm, EtOAc/hexane (1:2), followed byEtOAc/hexane (2:3)) to provide, after evaporation and drying, in vacuo,7.3 g (52%) of the benzyl-4-(2-hydroxyethoxy) epicatechin, as a foam orsolid, which was recrystallized from acetonitrile: mp 120-121° C.; 1HNMR (CDCl₃) δ 7.48-7.26 (m, 20H), 7.14 (d, J=1.5 Hz), 7.02, 6.97 (ABq,2H, J=8 Hz, A part d with J=1.5 Hz), 6.29, 6.26 (ABq, 2H, J=2 Hz), 5.19(s, 2H), 5.17 (s, 2H), 5.10 (s, 1H), 5.08, 5.02 (ABq, 2H, partiallyconcealed), 5.00 (s, 2H), 4.59 (d, 1H, J=2.5 Hz), 3.95 (br, 1H),3.82-3.74 (m, 1H), 3.72-3.57 (m, 3H), 2.17 (br, 1H), 1.64 (d, 1H, J=5.5Hz); IR (film) 3450 (br), 1616, 1592, 1512, 1152, 1114, 735, 697 cm⁻¹.Anal. Calcd. for C₄₅H₄₂O₈: C, 76.04; H, 5.96. Found: C, 76.57; H, 6.02.

EXAMPLE 5 Preparation of O-Benzylepicatechin (4β→8) Oligomers

To a cold (0° C.), stirred solution of the benzyl-4-(2-hydroxyethoxy)epicatechin according to Example 4 (3.28 g, 4.6 mmol) and thetetra-O-benzyl-epicatechin according to Example 3 (12.0 g, 18.4 mmol, 4eq.) in anhydrous THF (40 mL) and anhydrous methylene chloride (50 mL),was added dropwise, in 10 min, titanium tetrachloride (4.6 mL of 1 MTiCl₄ in methylene chloride). (H. Kawamoto et al, Mokazai Gakkaishi, 37,(5) 448-493 (1991)) The resulting amber-colored solution was stirred inthe ice bath for 5 min, then at room temperature for 90 min. Thereaction was terminated by addition of 30 mL of saturated aqueous NaHCO₃and 100 mL of water (resulting pH: 8). The resulting mixture wasextracted with methylene chloride (2×20 mL). The combined organic layerswere washed with 50 mL of water, dried over MgSO₄, evaporated and driedin vacuo. The resulting glass deposited a pink solid upon dissolution inmethylene chloride (CH₂Cl₂) and standing at room temperature. The solidwas filtered off, washed with 3×15 mL of CH₂Cl₂/hexane (1:1), and driedin vacuo to obtain 6.1 g of recovered tetra-O-benzylepicatechin. Fromthe evaporated mother liquor, the oligomers were isolated by columnchromatography on silica gel (45×5.2 cm). Elution withCH₂Cl₂/hexane/EtOAc (13:13:1) provided an additional 4.9 g of recoveredtetra-O-benzylepicatechin, followed by 2.17 g of crude O-benzyl dimer.Elution of the dimer was completed using methylene chloride/hexane/EtOAc(10:10:1). Elution of 0.98 g of crude O-benzyl trimer and 0.59 g ofhigher oligomers was obtained using methylene chloride/hexane/EtOAc(8:8:1 to 6:6:1). The dimer and the trimer were further purified bypreparative HPLC on a silica gel column, using ethyl acetate/hexane orethyl acetate/isooctane as eluent. Peak detection was performed with aUV detector at 265 or 280 nm. Trimer: MS (MALDI-TOF, DHBA matrix) m/z(M+H⁺) 1949.4; calcd. for C₁₂₉H₁₁₀O₁₈: 1947.8; (M+Na⁺) 1971.2; calcd.for C₁₂₉H₁₁₀O₁₈Na: 1969.8; (M+K⁺) 1988.3; calcd. for C₁₂₉H₁₁₀O₈K:1985.7.

EXAMPLE 6 Preparation of Epicatechin Dimer

To a solution of the O-benzyl-dimer according to Example 5 (22.3 mg,17.2 μmol) in 0.5 mL of ethyl acetate was added sequentially, 2 mL ofmethanol and 7.2 mg of 10% Pd/C. The mixture was stirred under 1 bar ofH₂ for 3 hours and filtered over cotton. The filtration residue waswashed with methanol and the combined filtrates were evaporated. An NMRspectrum of the crude product indicated the presence of benzylatedmaterial. The procedure was therefore repeated, with the amount ofcatalyst increased to 17.5 mg and the time extended to 3.7 h. The crudepolyphenol dimer (9.6 mg) was purified by preparative HPLC (C₁₈ reversephase column water/methanol (85:15) with addition of 0.50%. acetic acid,detection at 265 nm) to provide 4.5 mg (45%) of polyphenol dimer as anamorphous film. ¹H NMR (300 MHz, acetone-d₆/D₂O 3:1 (v/v), TMS) δ 7.19(br, 1H), 7.01 (overlapping s+br, 2H), 6.86-6.65 (m, 4H), 6.03 (br, 3H),5.10 (br, 1H), 5.00 (br, 1H), 4.69 (br, 1H), 3.97 (s, 1H), 2.92, 2.76(br ABq, 2H, J=17 Hz); MS (MALDI-TOF, DHBA matrix) m/z (M+K⁺) 616.8;calcd. for C₃₀H₂₆O₁₂K: 617.1; (M+Na⁺) 600.8; calcd. for C₃₀H₂₆O₁₂Na:601.1.

EXAMPLE 7 Preparation of O-Benzylepicatechin Dimer Bisgallate

To a solution of tri-O-benzyl gallic acid (38 mg, 87 μmol, 5 eq.), DMF(1 μL) in methylene chloride (0.6 mL), was added oxalyl chloride (15 μL,172 μmol, 10 eq.). The resulting reaction mixture was stirred at roomtemperature for approximately 1 hour, evaporated and dried in vacuo toprovide tri-O-benzyl galloyl chloride. A solution of the O-benzyl-dimeraccording to Example 5 (22.5 mg, 17.3 μmol) in anhydrous pyridine (0.5mL) was added to the crude galloyl chloride at room temperature, and theresulting mixture was stirred for 44.5 h. After addition of 20 μL ofwater, stirring was continued for 2.5 h, followed by addition of 10 mLof 5% HCl. The resulting mixture was extracted with methylene chloride(3×5 mL), the combined organic phases were dried over MgSO₄, evaporatedand purified by filtration over silica gel using with EtOAc/CHCl₃(1:19). Concentration of the eluate and drying in vacuo yielded 36.0 mg(97%) of the O-benzyl dimer bisgallate as a colorless film:[α]_(D)−53.3°, [α]₅₄₆−65.6° (CH₂Cl₂, c 15.7 g/L); IR (film) 1720, 1591,1498, 1428, 1196, 1112, 736, 696 cm⁻¹; MS (MALDI-TOF, DHBA matrix) m/z(M+K⁺) 2181.8; calcd. for C₁₄₂H₁₁₈O₂₀K: 2181.8; (M+Na⁺) 2165.9; calcd.for C₁₄₂H₁₁₈O₂₀Na: 2165.8.

EXAMPLE 8 Preparation of Epicatechin Dimer Bisgallate

To a solution of the O-benzyl dimer bisgallate according to Example 7(33.8 mg, 15.8 μmol) in 4 mL of THF was added sequentially 4 mL ofmethanol, 0.2 mL of water, and 42 mg of 20% Pd(OH)₂/C. The mixture wasstirred under 1 bar of H₂ for 75 minutes and filtered over cotton. Thefiltration residue was washed with 2.2 mL of methanol/H₂O (10:1) and thecombined filtrate was concentrated under reduced pressure to provide14.2 mg of yellowish, amorphous crude product. A 7.2 mg aliquot waspurified by preparative HPLC (silica gel, ethyl acetate/hexane;detection at 280 nm) to yield 5.0 mg (71%) of the polyphenol dimerbisgallate as a turbid pinkish glass from which small amounts of ethanoland acetic acid could not be removed: ¹H NMR (acetone-d₆/D₂O 3:1 v/v,TMS, most signals broad) δ 7.08 (s, 2H, sharp), 7.1-6.7 (m, 7H), 6.66(d, 1H, sharp, J=8 Hz), 6.17 (s, 1H), 5.94 (s, 2H), 5.70 (s, 1H), 5.49(s, 1H), 5.44 (s, 1H), 4.9 (very br, 1H), 4.80 (s, 1H), 3.08, 2.88 (ABq,2H, J=17 Hz, A part d, J=4 Hz); MS (MALDI-TOF, DHBA matrix) m/z (M+Na⁺)904.9; calcd. for C₄₄H₃₄O₂₀Na: 905.2.

EXAMPLE 9 Preparation of O-Benzylepicatechin Trimer Trisgallate

Using the procedure described in Example 7, O-benzyl trimer trisgallatewas obtained from the O-benzyl trimer according to Example 5 in 78%yield after purification by HPLC (conditions: silica gel, ethylacetate/hexane, 280 nm); 1H NMR: extremely complex; IR (film) 3031,1719, 1594, 1498, 1428, 1116, 735, 696 cm⁻¹.

EXAMPLE 10 Preparation of Epicatechin Trimer Trisgallate

Using the procedure described in Example 8, polyphenol trimertrisgallate was obtained from the O-benzyl trimer trisgallate accordingto Example 9 in 60% yield after purification by HPLC. (C₁₈ reverse phasegradient of 15-25% B in A, where A is 0.5 vol. % acetic acid (AcOH) inwater and B is 0.5% AcOH in ethanol; 280 nm); ¹H NMR (300 MHz,D₂O/acetone-d₆ 1:3 (v/v)) δ 7.10 (s, 2H), 7.1-6.88 (m, 7H), 6.82-6.70(m, 3H), 6.68-6.60.

EXAMPLE 11 Preparation of 8-Bromo-5,7,3′,4′-tetra-O-benzylepicatechin

Method A: To a solution of 116 mg (178 μmol) oftetra-O-benzylepicatechin in 4 mL of anhydrous CH₂Cl₂ was added with icecooling and stirring 32 mg (180 μmol) of N-bromosuccinimide (NBS).Stirring at 0° C. was continued for 100 min, the solution wasconcentrated, and the residue was purified by chromatography on silicagel (15×1.8 cm) with CHCl₃/EtOAc (25:1). Crystallization fromCHCl₃/ethanol gave 110 mg (85%) of a colorless, cotton-like solid. Mp137.5° C.; [α]_(D)−50.4°, [α]₅₄₆−60.7° (c 17.3 g/L, EtOAc); ¹H NMR (300MHz, CDCl₃, TMS) δ 7.5-7.25 (m, 20H), 7.23 (d, 1H, J=1.5 Hz), 7.03, 6.98(ABq, 2H, J=8.5 Hz, A part d with J=1 Hz), 6.25 (s, 1H), 5.22 (s, 2H),5.19 (s, 2H), 5.11 (s, 2H), 5.02, 4.96 (ABq, 2H, J=9 Hz), 4.98 (s, 1H),4.27 (br s, 1H), 3.04, 2.90 (ABq, 2H, J=17.5 Hz, both parts d with J=1.5and 4 Hz, resp.), 1.58 (d, 1H, J=4.5 Hz); ¹³C NMR (75 MHz, CDCl₃) δ156.86, 154.79, 151.65, 149.09, 148.73, 137.31, 137.15, 136.77, 136.72,130.82, 128.67, 128.65, 128.58, 128.56, 128.09, 127.98, 127.87, 127.50,127.31, 127.25, 127.13, 118.91, 115.17, 113.07, 102.85, 93.07, 78.62,71.35, 71.20, 70.31, 65.92, 28.00; IR (mineral oil suspension) 3571,1606, 1581, 1518, 1184, 1129, 771, 732, 694 cm⁻¹; MS m/z 399/397 (1/1%),332 (1% 0), 181 (8%), 91 (100%). Anal. calcd. for C₄₃H₃₇O₆Br: C, 70.78;H, 5.11. Found: C, 70.47; H, 5.10.

Method B: To 563 mg (771 μmol) of 5,7,3′,4-tetra-8-bromocatechin,prepared by the method described in Example 1, in 5 mL of CH₂CL₂ wasadded at room temperature all at once 425 mg (1.00 mmol) of Dess-Martinperiodinane. Water-saturated CH₂Cl₂ was added dropwise within 40 min toproduce a slight turbidity. After another 20 min, 20 mL each ofsaturated NaHCO₃ solution and a 10% aqueous solution of Na₂S₂O₃.5H₂Owere added. The phases were separated and the aqueous phase extractedwith 3×15 mL of ether. The combined organic phases were concentrated andthe residue filtered over silica gel (20×2.5 cm, ether/hexane 1:1). Theeluate was evaporated and dried in vacuo to obtain 522 mg (93%) of theketone as a colorless foam: ¹H NMR (CDCl_(3 δ) 7.47-7.25 (m, 20H), 7.04(d, 1H, J=1 Hz), 6.85, 6.81 (ABq, 2H, J=8.5 Hz, B part d with=8.5 Hz),3.52, 3.48 (ABq, 2H, J=21.5 Hz); ¹³C NMR (CDCl_(3 δ) 203.99, 155.55,155.40, 150.68, 148.98, 137.06, 136.90, 136.28, 136.04, 128.64, 128.62,128.46, 128.41, 128.22, 128.05, 127.78, 127.76, 127.35, 127.17, 127.13,127.08, 126.99, 118.86, 114.59, 112.43, 103.54, 93.96, 93.87, 82.91,71.25, 71.04, 70.98, 70.38, 33.30; IR (film) 1734, 1605, 1513, 1099, 737696 cm⁻¹.

To 598 mg (822 μmol) of the above crude ketone in 8.2 mL of anhydrousTHF was added dropwise within 10 min 1.23 mL of a 1 M solution oflithium tri-sec-butylborohydride (L-Selectride®). After stirring at −78°C. for 3 h, starting material was still detectable in the reactionmixture by thin layer chromatography, “TLC,” (SiO₂, EtOAc/hexane 1:3),and another 1.23 mL of the reducing agent was added. Stirring wascontinued for another 4 h while the temperature was gradually allowed torise to −4° C. Aqueous NaOH (2.5 M, 6 mL) and 4 mL of 35% aqueous H₂O₂were added with continued cooling; the resulting exotherm raised thebath temperature to +12° C. Stirring in the water bath was continuedovernight, then the mixture was partially evaporated, and 20 mL etherand 10 mL of EtOAc were added. The phases were separated, and theaqueous phase was extracted with 50 mL of EtOAc. The combined organicphases evaporated, and the residue was purified by chromatography onsilica gel (23×2.5 cm) with EtOAc/hexane 1:3 to obtain 327 mg (55%) ofthe product as a light-yellow foam.

EXAMPLE 12 Preparation of O-Methylepicatechin Tetramer

The O-methylepicatechin trimer (prepared according to Examples 1 through5, except that in Example 1, methyl iodide or dimethyl sulfate andpotassium carbonate in acetone is used to prepare the protected monomer,tetra-O-methylcatechin) is brominated in position 8 of the topepicatechin moiety using either of the procedures of Example 11. Theresulting bromo derivative is reacted with5,7,3′,4′-tetra-O-methyl-4-(2-hydroxyethoxy)epicatechin according toExample 5 to yield a mixture of tetramers having the fourth epicatechinmoiety attached to the 6-positions predominantly of the bottom andcenter epicatechin moieties, as well as higher oligomers. The desiredintermediate,

is isolated by preparative HPLC as in Example 11. The purifiedintermediate is de-brominated by treatment of its THF solution at lowtemperature, preferably at −78° C., with an excess of an alkyllithium,preferably n- or tert-butyllithium, and protonation of the resultingsolution or suspension of the lithiated protected branched tetramer byaddition of a weak proton acid, such as water or an alcohol.

EXAMPLE 13 Preparation of O-Benzylepicatechin Tetramer Tetragallate

Using the procedure described in Example 7, the O-benzylepicatechintetramer tetragallate is obtained from the O-benzylepicatechin tetrameraccording to Example 12.

EXAMPLE 14 Preparation of Epicatechin Tetramer Tetragallate

Using the procedure described in Example 8, the epicatechin tetramertetragallate is obtained from the O-benzylepicatechin tetramertetragallate according to Example 13.

EXAMPLE 15 3,5,7,3′,4-Penta-O-benzyl-8-bromoepicatechin

To 53 mg (1.3 mmol) of sodium hydride (60% suspension in mineral oil)was added with stirring at 0° C. under N₂ 738 mg (1.01 mmol) of5,7,3′,4-tetra-O-benzyl-8-bromoepicatechin in 2 mL of anhydrous DMF.After 10 min, 0.18 mL (1.5 mmol) of neat benzyl bromide was added. Themixture was stirred at 0° C. for 145 min and at room temperature for 5.5h, then 0.1 mL of water was added. Chromatography on SiO₂ (27×2.6 cm)with EtOAc/hexane 1:4 and drying in vacuo (room temperature, then 80°C.) yielded 650 mg (78%) of the product as a yellowish glass:[α]_(D)−52.6°, [α]₅₄₆−63.4° (EtOAc, c 17.9 gL⁻¹); ¹H NMR (CDCl₃) δ7.50-7.14 (m, 23H), 6.99 (m, 2H), 6.94, 6.91 (ABq, 2H, J=8.5 Hz, A partd with J=1.5 Hz), 6.23 (s, 1H), 5.19 (s, 2H), 5.11 (s, 5H), 4.97 (S,2H), 4.38, 4.30 (ABq, 2H, J=12.5 Hz), 3.97 (narrow m, 1H), 2.95, 2.80(ABq, 2H, J=17 Hz, both parts d with J=3.5 and 4.5 Hz, resp.); ¹³C NMR(CDCl₃) δ 156.44, 154.62, 151.94, 148.65, 137.92, 137.41, 137.26,136.75, 136.71, 131.68, 128.56, 128.53, 128.38, 128.12, 128.00, 127.85,127.70, 127.62, 127.43, 127.33, 127.25, 127.19, 127.02, 119.15, 114.74,113.29, 103.40, 93.11, 92.76, 78.06, 72.13, 71.32, 71.26, 71.21, 70.83,70.22, 24.73; IR (film) 1605, 1580, 1513, 1454, 1346, 1265, 1125, 1095,735, 697; IR (film) 1605, 1580, 1513, 1454, 1346, 1265, 1125, 1095, 735,697 cm⁻¹. Anal. Calcd. for C₅₀H₄₃O₆Br: C, 73.26; H, 5.29. Found C,72.81; H, 5.12.

EXAMPLE 16 5,7,3′,4-Tetra-O-benzyl-6,8-dibromoepicatechin

To a solution of 334 mg (914 μmol) of 5,7,3′,4-tetra-O-benzylepicatechinin 10 mL of anhydrous CH₂Cl₂ was added with ice cooling all at once 192mg (1.08 mmol) of recrystallized ^(N)-bromosuccinimide (NBS). Thereaction mixture was stirred at 0° C. for 45 min and at room temperaturefor 17 h. A solution of 200 mg of Na₂S₂O₃.5H₂O in 5 mL of water wasadded. After brief stirring, the phases were separated, the aqueousphase was extracted with 5 mL of CH₂Cl₂, and the combined organic phaseswere dried over MgSO₄ and evaporated. Chromatography on silica gel(30×2.6 cm) with EtOAc/CHCl₃/hexane 1:12:7 (to remove a trace byproduct)then 3:12:7, was followed by evaporation and drying in vacuo to give 362mg (87%) of the dibromide as a colorless foam: [α]₅₄₆−58.2°, (EtOAc, c13.5 gL⁻¹); ¹H NMR (CDCl₃) δ 7.64 (d, 2H, J=7 Hz), 7.52-7.26 (m, 18H),7.17 (s, 1H), 7.03, 6.97 (s, 2H), 5.20 (s, 2H), 5.17 (s, 2H), 5.03 (s,2H), 5.01, 4.97 (ABq, 2H, J=11 Hz), 4.99 (s, 1 h), 4.19 (narrow m, 1H),3.04, 2.87 (ABq, J=17.5 Hz, both parts d with J=1.5 and 3.5 Hz, resp.),1.55 (d, 1H, J=3.5 Hz); ¹³C NMR (CDCl₃) δ 154.43, 152.57, 151.09,149.03, 148.82, 137.10, 136.94, 136.50, 136.37, 130.13, 128.52, 128.50,128.48, 128.47, 128.43, 128.35, 128.32, 128.16, 127.821 127.81, 127.36,127.20, 118.81, 115.06, 112.91, 112.30, 105.23 103.25, 78.80, 74.61,74.55, 71.24, 71.14, 65.33, 28.75; IR (film) 1734, 1606, 1513, 1369,1266, 1184, 1113, 1083, 735, 697 cm⁻¹. Anal. Calcd, for C₄₃H₃₆O₆Br₂: C,63.88; H, 4.49. Found: C, 64.17; H, 4.45.

EXAMPLE 17 5,7,3′,4′-Tetra-O-benzyl-6,8,6′-tribromoepicatechin

To a solution of 1.72 g (2.65 mmol) of5,7,3′,4-tetra-O-benzylepicatechin in 26 mL of anhydrous CH₂Cl₂ wasadded with ice cooling all at once 1.89 g (10.6 mmol) of recrystallizedN-bromosuccinimide. The reaction mixture was stirred at 0° C. for 1 hand at room temperature for 20 h. A solution of 3 g of Na₂S₂O₃.5H₂O in25 mL of water was added. Partial phase separation occurred only afteraddition of 30 mL of brine, 230 mL of water, and 130 mL of CH₂Cl₂.Residual emulsion was set aside, the aqueous phase was extracted with100 mL of CH₂Cl₂, and this organic phase and 200 mL of water were shakenin a separatory funnel with the emulsion. Again phase separation wasincomplete, and the remaining emulsion was extracted a last time with100 mL of CH₂Cl₂. The combined organic phases were dried over MgSO₄ andconcentrated. Chromatography on silica gel (17×4.5 cm) withEtOAc/CHCl₃/hexane 1:12:7, then 1:15:4 was followed by evaporation anddrying in vacuo to give 2.01 g (85%) of the tribromide as a light-tansolid. The analytical sample was obtained by crystallization fromCHCl₃/EtOH: mp 154-156° C.; [α]_(D)−112°, [α]₅₄₆−135° (EtOAc, c 9.7gL⁻¹); ¹H NMR (CDCl₃ δ 7.66 (d, 2H, 6.5 Hz), 7.52 (d, 2H, J=6.5 Hz),7.48-7.26 (m, 17H), 7.14 (s, 1H), 5.28 (s, 1H), 5.23 (s, 2H), 5.17 (s,2H), 5.06 (s, 2H), 5.02 (s, 2H), 4.44 (narrow m, 1H), 3.10, 2.95 (ABq,J=17 Hz, A part br, B part d with J=4 Hz), 1.35 (d, 1H, J=4 Hz); ¹³C NMR(CDCl₃ δ 154.54, 152.53, 151.09, 149.15, 148.32, 136,49, 136.44, 136.40,136.31, 128.72, 128.54, 128.52, 128.48, 128.42, 128.36, 128.33, 128.16,128.02, 127.89, 127.41, 127.27, 118.84, 114.58, 112.30, 111.42, 105.38,103.14, 78.61, 74.62, 74.58, 71.46, 70.96, 62.66, 28.99; IR (film) 1499,1385, 1367, 1266, 1182, 1109, 1083, 734, 695 cm⁻¹. Anal. Calcd. forC₄₃H₃₅O₆Br₃: C, 58.20; H, 3.98. Found: C, 58.52; H, 3.80.

EXAMPLE 18(2R,3S,4S)-5,7,3′,4′-Tetra-O-benzyl-8-bromo-4-(2-hydroxyethoxy)epicatechin

Method A: To a solution of 202 mg (284 μmol) of(2R,3S,4S)-5,7,3′,4′-tetra-O-benzyl-4-(2-hydroxyethoxy)epicatechin in 4mL of CH₂Cl₂ was added at −78° C. all at once 51 mg (286 μmol) ofrecrystallized N-bromosuccinimide. The reaction mixture was stirred inthe thawing cold bath, which after 65 min had reached 0° C. A solutionof 50 mg of Na₂S₂O₃.5H₂O in 1 mL of water was added, the cold bath wasremoved, and the mixture was stirred for 15 min at room temperature. Thephases were separated, and the organic phase was extracted with 5 mL ofCH₂Cl₂. The combined organic phases were dried over MgSO₄, concentrated,and purified via chromatography on silica gel (33×1.6 cm) withEtOAc/hexane 1:1 (Note 1). After starting material and mixed fractionscontaining comparable concentrations of both components had been eluted,fractions consisting mostly of the desired product were collected. Thesefractions were further purified by preparative HPLC (Whatman Partisil10,500×9.4 mm, EtOAc/hexane 1:1, 5 mL/min, detection at 280 nm). Themajor peak with t_(R) 14.4 min was isolated: ¹H NMR (CDCl₃) δ 7.49-7.25(m, 20H), 7.23 (d, 1H, J=1 Hz), 7.05, 6.98 (ABq, 2H, J=8 Hz, A part dwith J=1.5 Hz), 6.28 (s, 1H), 5.23 (s, 3H), 5.19 (s, 2H), 5.12 (s, 2H),5.05, 4.99 (ABq, 2H, J=11.5 Hz), 4.63 (d, 1H, J=3 Hz), 4.03 (br, 1H),3.83-3.76 (m, 1H), 3.74-3.56 (m, 3H), 2.11 (br, 1H), 1.57 (br, 1H); ¹³CNMR (CDCl₃) δ 158.30, 156.61, 152.17, 149.09, 148.73, 137.18, 137.07,136.39, 136.02, 130.04, 128.68, 128.61, 128.49, 128.46, 128.33, 127.98,127.79, 127.60, 127.45, 127.23, 126.93, 118.95, 115.16, 113.24, 103.36,92.78, 75.05, 71.30, 71.21, 71.09, 70.83, 70.70, 70.23, 67.90, 61.89; IR(film) 3380 (br), 1603, 1577, 1514, 1187, 1130, 1111, 733, 696 cm⁻¹.

Method B: To 44.1 mg (43.3 μmol) of the bis(TBDMS) ether of Example 19,dissolved in 0.4 mL of anhydrous THF, was added 0.19 mL of atetrabutylammonium fluoride solution (1 M in THF). The mixture wasstirred in a closed flask for 4 hours, then evaporated, and the residuewas purified via chromatography on silica gel (15×1.8 cm) withEtOAc/CHCl₃/hexane 1:12:7 (to remove a forerun), then 1:19:0. The eluatewas evaporated and dried in vacuo to yield 32.7 mg (96%) of the productas a colorless film.

EXAMPLE 19(2R,3S,4S)-5,7,3′,4′-Tetra-O-benzyl-3-O-(tert-butyldimethylsilyl)-4-[2-[(tert-butyldimethylsilyl)oxy]ethoxy]epicatechin

To solution of 2.18 g (3.07 mmol) of(2R,3S,4S)-5,7,3′-4′-tetra-O-benzyl-4-(2-hydroxyethoxy)epicatechin and0.63 g (9.2 mmol) of imidazole in 5 mL of anhydrous DMF was added atroom temperature, all at once, 1.30 g (8.6 mmol, 2.8 eg.) oftert-butyldimethylsilyl chloride. The mixture was stirred at roomtemperature in a stoppered flask for 24 h and then directly filteredover silica gel (33×3.7 cm) with EtOAc/hexane 1:6 to give, afterevaporation and drying in vacuo, 2.63 g (91%) of the product as acolorless glass: [α]_(D)+3.9°, [α]₅₄₆+4.7° (EtOAc, c 9.0 gL⁻¹); ¹H NMR(CDCl₃) δ 7.51-7.28 (m, 20H), 7.12 (d, 1H, J=1 Hz), 6.98, 6.93 (ABq, 2H,J=8 Hz, A part d with J=1 Hz), 6.24, 6.22 (ABq, 2H, J=2 Hz), 5.19, 5.14(ABq, 2H, partially concealed), 5.17 (s, 2H), 5.09-4.96 (2 overlappingABq, 4H), 4.50 (d, 1H, J=3 Hz), 3.89 (br d, 1H, J=2.5 Hz), 3.69 (m, 4H),0.88 (s, 9H), 0.67 (s, 9H), 0.04 (s, 3H), 0.03 (s, 3H), −0.21 (s, 3H),−0.48 (s, 3H); ¹³C NMR (CDCl₃) δ 160.12, 159.39, 156.63, 148.88, 148.30,137.37, 137.02, 136.83, 132.65, 128.53, 128.49, 128.42, 128.38, 127.94,127.82, 127.75. 127.67, 127.62, 127.51, 127.33, 127.26, 120,14, 115.28,114.29, 102.23, 94.28, 93.17, 75.22, 71.5, 71.40, 70.63, 70.32, 70.11,69.98, 69.61, 62.71, 25.95, 25.59, 18.38, 17.90, −5.10, −5,18, −5.25,−5.40; IR (film) 2952, 2928, 2855, 1616, 1593, 1257, 1153, 1136, 1108,835, 777, 735, 696 cm⁻¹. Anal. Calcd, for C₅₇H₇₀O₈Si₂: C, 72.88; H,7.51. Found: C, 73.35; H, 7.04.

EXAMPLE 20(2R,3S,4S)-5,7,3′,4′-Tetra-O-benzyl-8-bromo-3-O-(tert-butyldimethylsilyl)-4-[2-[tert-butyldimethylsilyl)oxy]ethoxy]epicatechin

To a solution of 2.61 g (2.78 mmol) of(2R,3S,4S)-5,7,3′,4′-tetra-O-benzyl-3-O-(tert-butyldimethylsilyl)-4-[2-[(tert-butyldimethylsilyl)oxy]ethoxy]epicatechin,in 35 mL of CH₂Cl₂ was added at −78° C., all at once, 500 mg (2.81 mmol)of recrystallized N-bromosuccinimide. The reaction mixture was stirredin the thawing cold bath, which after 6 h had reached +20° C. A solutionof 0.5 g of Na₂S₂O₃.5H₂O in 10 mL of water was added, the cold bath wasremoved, and the mixture was stirred for 10 min at room temperature. Thephases were separated, and the organic phase was extracted with 5 mL ofCH₂Cl₂. The combined organic phases were concentrated and filtered oversilica gel with EtOAc/hexane 1:4. Evaporation and drying in vacuoresulted in 2.72 g (96%) of the product as a colorless glass:[α]_(D)−25.8°, [α]₅₄₆−31.6° (EtOAc, c 20.2 gL⁻); ¹H NMR (CDCl₃) δ7.51-7.25 (m, 20H), 7.22 (s, 1H), 6.98, 6.94 (ABq, 2H, J=8 Hz, A partbr), 6.22 (s, 1H), 5.30 (s, 1H), 5.19 (s, 2H), 5.17 (s, 2H), 5.11 (s,2H), 5.06, 4.98 (ABq, 2H, J=12 Hz), 4.54 (d, 1H, J=3 Hz), 3.94 (br d,1H, J=2.5 Hz), 3.73-3.60 (m, 4H), 0.88 (s, 9H), 0.60 (s, 9H), 0.04 (s,3H), 0.03 (s, 3H), −0.24 (s, 3H), −0.56 (s, 3H); ¹³C NMR (CDCl₃) δ158.04, 156.11, 152,88, 148,92, 148.05, 137.42, 137.31, 136.62, 136.59,132.24, 128.59, 128.52, 128.41, 128.37, 128.01, 127.85, 127.69, 127.63,127.45, 127.31, 127.19, 126.99, 119.46, 115.41, 113.76, 103.75, 92.61,91.79, 75.78, 71.60, 71.05, 71.03, 70.61, 70.47, 70.14, 69.30, 62.65,25.94, 25.47, 18.39, 17.90, −5.10, −5.19, −5.50; IR (film) 2952, 2928,285, 1605, 1578, 1257, 1186, 1135, 1114, 835, 777, 735, 696 cm⁻¹. Anal.Calcd. for C₅₇H₆₉O₈BrSi₂: C, 67.24; H, 6.83. Found: C, 67.35; H, 6.57.

EXAMPLE 21(2R,3S,4S)-5,7,3′,4′-Tetra-O-benzyl-6,8,6′-tribromo-3-O-(tert-butyldimethylsilyl)-4-[2-[(tert-butyldimethylsilyl)oxy]ethoxy]epicatechin

To a solution of 96.0 mg (94.3 μmol) of(2R,3S,4S)-5,7,3′,4′-tetra-O-benzyl-8-bromo-3-O-(tert-butyldimethylsilyl)-4-[2-[(tert-butyldimethylsilyl)oxy]ethoxy]epicatechinin 1.2 mL of CH₂Cl₂ was added at room temperature, all at once (65 mg,365 μmol, 3.87 eq.) of recrystallized N-bromosuccinimide. The reactionmixture was held at room temperature for 20.5 h, then a solution of 0.5g of Na₂S₂O₃.5H₂O in 5 mL of water was added, and the mixture wasstirred for 10 min at room temperature. The phases were separated, andthe organic phase was extracted with 2×5 mL of CH₂Cl₂. The combinedorganic phases were concentrated and filtered over silica gel (34×1.1cm) with EtOAc/hexane 1:12. Evaporation and drying in vacuo resulted in90.3 mg (81%) of the product as a colorless glass [α]₅₄₆−74.1° (EtOAc, c9.0 gL⁻¹); ¹H NMR (CDCl₃) δ 7.64 (d, 2H, J=7 Hz), 7.60 (d, 2H, J=7 Hz),7.49-7.28 (m, 17H), 7.13 (s, 1H), 5.62 (s, 1H), 5.24, 4.97 (ABq, 2H.J=11 Hz), 5.16 (s, 4H), 5.09 (s, 2H), 4.53, 4.43 (ABq, 2H. J=2.5 Hz, Bpast br), 3.09-3 81 (m, 1H), 3.80-3.71 (m, 3H), 0.84 (s, 9H), 0.65 (s,9H), −0.02 (s, 3H), −0.16 (s, 3H), −0.57 (s, 3H) (one Si—CH₃ signalpresumably coinciding with TMS); ¹³C NMR (CDCl₃) δ 156.15, 154.11,153.92, 148.72, 148.65, 136.90, 136.69, 136.58, 136.38, 129.61, 128.52,128.50, 128.45, 128.43, 128.32, 128.16, 127.94, 127.91, 127.64, 127.44,127.33, 119.23, 115.83, 113.33, 110.94, 104.76, 103.01, 75.85, 75.64,74.56, 71.75, 71.50, 70.89, 70.79, 64.27, 62.55, 25.97, 25.58, 18.44,17.73, −5.24, −5.30, −5.80; IR (film) 2927, 2856, 1499, 1360, 1259,1106, 836 cm⁻¹.

EXAMPLE 22(2R,3S,4S)-5,7,3′4′-Tetra-O-benzyl-6,8,6′-tribromo-4-(2-hydroxyethoxy)epicatechin

To 73.4 mg (62.4 μmol) of the bis(TBDMS) ether in 0.4 mL of anhydrousTHF was added 0.25 mL of tetrabutylammonium fluoride solution (1 M inTHF). The mixture was stirred in a closed flask for 2.5 h, thenevaporated, and the residue was purified via chromatography on silicagel (15×1 cm) with EtOAc/hexane 1:2 (to remove a forerun), then 1:1. Theevaporated eluate was further purified by preparative thin layerchromatography (SiO₂, 200×200×2 mm, EtOAc/hexane 1:1) to yield 44.8 mg(76%) of the product as a colorless film: [α]_(D)−81.6°, [α]₅₄₆−98.3°(EtOAc, c 10.1 gL⁻¹); ¹H NMR (CDCl₃) δ 7.65 (d, 2H. J=6.5 Hz), 7.54 (d,2H. J=6.5 Hz), 7.48-7.24 (m, 17H), 7.13 (s, 1H), 5.57 (s, 1H), 5.24,5.08 (ABq, 2H. J=11 Hz), 5.22, 5.18 (ABq, 2H. J=11.5 Hz), 5.13 (s, 2H),5.06 (s, 2H), 4.45 (d, 1H, J=HZ), 4.25 (br, 1H), 3.84-3.76 (m, 1H),3.72-3.58 (m, 3H), 2.11 (br, 1H), 1.48 (br, 1H); ¹³C NMR (CDCl₃) 156.24,154.70, 151.52, 149.24, 148.39, 136.50, 136.38, 136.18, 128.60, 128.58,128.52, 128.51, 128.49, 128.44, 128.09, 128.06, 128.03, 127.94, 127.46,127.27, 118.92, 115.03, 112.99, 111.33, 105.40. 103.41, 76.04, 75.08,74.66, 71.50, 71.08, 71.03, 70.96, 64.12, 61.95; IR (film) 3500 (br),1580, 1500. 1365, 1262, 1193. 1121, 1097, 736, 696 cm⁻¹.

EXAMPLE 23[5,7,3,4′-Tetra-O-benzyl-8-bromo-3-O-(tert-butyldimethylsilyl)epicatechin]-(4,8)-(5,7,3′,4′-tetra-O-benzylepicatechin)

To a solution of 97.3 mg (95.6 μmol) of(2R,3S,4S)-5,7,3′,4′-tetra-O-benzyl-8-bromo-3-O-(tert-butyldimethylsilyl)-4-[2-[(tert-butyldimethylsilyl)oxy]ethoxy]epicatechinand 311 mg (478 μmol, 5 eq.) of 5,7,3′,4′-tetra-O-benzylepicatechin in0.85 mL of anhydrous THF and 1.1 mL of anhydrous CH₂Cl₂ was added withstirring and exclusion of moisture at 0° C., 0.10 mL (0.10 mmol) of a 1M solution of TiCl₄ in CH₂Cl₂. After 140 min at room temperature, 5 mLof saturated aq. NaHCO₃ and 10 mL of CH₂Cl₂ were added, the phases wereseparated, and the aqueous phase was extracted with 2×10 mL of CH₂Cl₂.The combined organic phases were dried over MgSO₄ and evaporated, andthe residue was filtered over silica gel with EtOAc/toluene 1:19.Evaporation and drying in vacuo gave 239 mg of a foam the components ofwhich could be separated only by preparative HPLC (Whatman Partisil 10,500×9.4 mm, EtOAc/toluene 1:24, 5 mL/min, detection at 290 nm). From 234mg of this mixture, 34.8 mg of the desired product was obtained at t_(R)10.3 min. Remaining minor impurities were removed by additionalpreparative HPLC (Whatman Partisil 10,500×9.4 mm, EtOAc/hexane 1:4, 5mL/min, detection at 280 nm, t_(R) 16.1 min) to yield 30.3 mg (21%) ofthe title compound as a glass: [α]_(D)+16.2°, [α]₅₄₆+19.4° (EtOAc, c12.3 gL⁻¹); ¹H NMR (CDCl₃) (two rotamers) δ 7.5-6.7 (m), 6.26 (s), 6.22(s), 6.14 (s), 6.09 (s), 5.99 (s), 5.52 (s), 5.44 (s), 5.20-4.71 (m),4.56, 4.37 (ABq, J=12.5 Hz), 4.12 (br), 3.90 (br s), 3.74 (br), 3.03,2.95 (ABq, minor rotamer, J=17 Hz, both parts d with J=2.5 and 3.5 Hz,resp.), 2.92, 2.81 (ABq, major rotamer, J=18 Hz, B part d win J=4.5 Hz),1.35 (s), 0.54 (s), 0.50 (s), −0.31 (s), −0.54 (s); IR (film) 2927,1603, 1512, 1267, 1111, 734, 696 cm⁻¹; MS (ES) m/z 1512.8, 1511.9,1510.8, 1509.8, 1508.8 (M+NH₄ ⁺; calcd. for ¹³C¹²C₉₁H₉₁⁸¹BrNO₁₂Si/¹²C₉₂H₉₁ ⁸¹BrNO₁₂Si/¹³C¹²C₉₁H₉₁ ⁷⁹BrNO₁₂Si/¹²C₉₂H₉₁⁷⁹BrNO₁₂Si: 1511.5/1510.5/1509.5/1508.5).

EXAMPLE 24(5,7,3′,4′-Tetra-O-benzyl-8-bromoepicatechin)-(4,8)-(5,7,3′,4′-tetra-O-benzylepicatechin)

Method A: To a solution of 78.6 mg (99.5 μmol) of(2R,3S,4S)-5,7,3′,4′-tetra-O-benzyl-8-bromo-4-(2-hydroxyethoxy)epicatechinand 324 mg (498 μmol, 5 eq.) of 5,7,3′,4′-tetra-O-benzylepicatechin in0.85 mL of anhydrous THF and 1.1 mL of anhydrous CH₂Cl₂ was added withstirring and exclusion of moisture at 0° C. 0.10 mL (0.10 mmol) of a 1 Msolution of TiC₄ in CH₂Cl₂. After 3.5 h at room temperature, 3 mL of ansaturated NaHCO₃ aqueous solution and 10 mL of CH₂Cl₂ were added, thephases were separated, and the organic phase was dried over MgSO₄ andevaporated. The residue was filtered over SiO₂ eluting sequentially withEtOAc/CHCl₃/hexane 1:12:7 (to remove most of the unreactedtetra-O-benzylepicatechin), then 1:19:0. The desired product wasisolated from the evaporated crude product by preparative HPLC (WhatmanPartisil 10,500×9.4 mm, EtOAc/hexane 1:4, 5 mL/min, detection at 280 nm,t_(R) 27.5 mm) to obtain 36.3 mg (26%) of a glass.

Method B: To a solution of 60.4 mg (46.5 μmol) of O-benzylatedepicatechin 4,8-dimer in 0.9 mL of anhydrous CH₂Cl₂ was added at −78° C.all at once 8.3 mg (47 μmol) of recrystallized N-bromosuccinimide. Thereaction mixture was stirred and allowed to thaw to 0° C. during 1.5 h,then stirred at 0° C. for 40 min. Thin Layer chromatography of themixture (SiO₂, EtOAc/toluene 1:9) showed that some material with thesame mobility as the starting material (R_(f) 0.49) was present besidesa product (R_(f) 0.43). The mixture was re-cooled to −40° C., and anadditional 2.2 mg (12 μmol) of NBS was added. After the mixture hadthawed to 0° C. within 70 min., the thin layer chromatogram of themixture remained unchanged, and the reaction was terminated by brieflystirring at room temperature with a solution of 0 1 g of Na₂S₂O₃.5H₂O in2 mL of water. The phases were separated, and the aqueous phase wasextracted with 5 mL of CH₂Cl₂. Evaporation, filtration over silica gel(10×1.1 cm) with EtOAc/CH₂Cl₂/hexane 1:6:3, and again evaporation gave65 mg of a crude mixture which was separated by preparative TLC (SiO₂,200×200×2 mm, EtOAc/toluene 1:15, 2 developments) and additionallypurified by preparative HPLC (Whatman Partisil 10, 500×9.4 nm,EtOAc/hexane 1:4, 5 mL/min, detection at 280 nm). The major productobtained thereby was identical by NMR with the one obtained above:[α]_(D), [α]₅₄₆+0.6° (EtOAc, c 8.4 gL⁻¹); ¹H NMR (CDCl₃ (two rotamers) δ7.5-6.8 (m), 6.78 (d, J=8 Hz), 6.74 (d, J=1 Hz), 6.34 (s), 6.27 (dd,J=1, 8 Hz), 6.19 (s), 6.16 (s), 6.02 (s), 5.56 (s), 5.36 (s), 5.2-4.95(m), 4.9-4.7 (m), 4.60, 4.36 (ABq, J=12 Hz), 4.33 (br), 4.11 (br), 3.99(s), 3.80 (br), 3.08-2.80 (2 ABq, minor rotamer A part at 3.04, J=17.5Hz, B part not discernible; major rotamer at 2.96, 2.85, J=18 Hz, B partd with J=4.5 Hz), 1.66 (d, J=5 Hz), 1.58 (d, J=5 Hz), 1.40 (d, J=3.5Hz), 1.28 (partially overlapping with solvent-derived impurity); IR(film) 1604, 1512, 1266, 1117, 735, 696 cm⁻¹; MS (ES) m/z 1398.6,1397.6, 1396.6, 1395.6, 1394.6 (M+NH₄ ⁺; calcd. for ¹³C¹²C₈₅H₇₇⁸¹BrNO₁₂/¹²C₈₆H₇₇ ⁸¹BrNO₁₂/¹³C¹²C₈₅H₇₇ ⁷⁹BrNO₁₂/¹²C₈₆H₇₇ ⁷⁹BrNO₁₂:1397.5/1396.5/1395.5/1394.5).

EXAMPLE 25 Cytotoxic Activity

The epicatechin dimer bisgallate (abbreviated ECDG) and epicatechintrimer trisgallate (abbreviated ECTG) were screened for activity againstcertain breast cancer cell lines, and the results are presentedgraphically in FIGS. 1(a)-(d).

All human tumor cell lines were obtained from the American Type CultureCollection. Cells were grown as monolayers in IMEM containing 10% fetalbovine serum without antibiotics. The cells were maintained in ahumidified, 5% CO₂ atmosphere at 37° C.

After trypsinization, the cells were counted and adjusted to aconcentration of 1,000-2,000 cells per 100 mL. Cell proliferation wasdetermined by plating the cells (1,000-2,000 cells/well) in a 96 wellmicrotiter plate. After addition of 100 μL cells per well, the cellswere allowed to attach for 24 hours. At the end of the 24 hour period,various polyphenol derivatives were added at different concentrations toobtain dose response results. The polyphenols were dissolved in media ata 2 fold concentration and 100 μL of each solution was added intriplicate wells. On consecutive days, the plates were stained with 50μL crystal violet (2.5 g crystal violet dissolved in 125 mL methanol,375 mL water), for 15 min. The stain was removed and the plate wasgently immersed into cold water to remove excess stain. The washingswere repeated two more times, and the plates allowed to dry. Theremaining stain was solubilized by adding 100 μL of 0.1 M sodiumcitrate/50% ethanol to each well. After solubilization, the number ofcells were quantitated on an ELISA plate reader at 540 nm (referencefilter at 410 nm).

Cancer cell line growth at the end of four days was plotted as thepercent growth of the control and is shown in FIGS. 1(a)-(d) as bargraphs. Error bars represent +/− standard deviation of three replicatemeasurements. The data indicated that the monomer (epicatechin) andsynthetic epicatechin dimer showed no cytotoxicity against the breastcancer cell lines investigated. However, the synthetic epicatechin dimerbisgallate and synthetic epicatechin trimer trisgallate elicited acytotoxic effect equivalent to the pentamer and/or epigallocatechingallate, especially at higher dosages.

It was surprisingly found that the dimer bisgallate and trimertrisgallate exhibited greater antineoplastic activity when compared tothe underivatized dimer and trimer. These results indicate thatgallation of the previously inactive cocoa procyanidin oligomerssubstantially increases the antineoplastic activity of the compounds.

1. A blocked, hydroxy-protected epicatechin or catechin monomer havinghalo blocking group(s) at the 8, or at the 6 and 8, or at the 6, 8, and6′ possition(s) and hydroxy-protecting groups at the 5, 7, 3′, and 4′positions.
 2. A blocked, hydroxy-protected epicatechin or catechinmonomer having halo blocking group(s) at the 8, or at the 6 and 8, or atthe 6, 8, and 6′ possition(s) and hydroxy-protecting groups at the 3, 5,7, 3′, and 4′ positions.
 3. The blocked, hydroxy-protected monomer ofclaim 1 or 2, wherein the halo blocking group(s) are bromo group(s). 4.The blocked, hydroxy-protected monomer of claim 2, wherein the haloblocking group(s) are bromo group(s); wherein the hydroxy-protectinggroups at the 5, 7, 3′, and 4′ positions are benzyl groups or methylgroups; and wherein the hydroxy-protecting group at the 3 position is abenzyl group or a tert-butyldimethylsilyl group.
 5. The blocked,hydroxy-protected monomer of claim 1, wherein the halo blocking group(s)are bromo group(s) and wherein the hydroxy-protecting groups at the 5,7, 3′, and 4′ positions are benzyl groups.
 6. The blocked,hydroxy-protected monomer of claim 1, which is the5,7,3′,4′-tetra-O-benzyl-8-bromoepicatechin.
 7. The blocked,hydroxyl-protected monomer of claim 2, which is5,7,3′,4′-tetra-O-benzyl-8-bromo-3-O-(tert-butyldimethylsilyl)epicatechin.
 8. An activated, blocked, hydroxy-protected epicatechin orcatechin monomer having a C₂-C₆ alkoxy group with a terminal hydroxygroup at the 4 position, having halo blocking group(s) at the 8position, or at the 6 and 8 positions, or at the 6, 8, and 6′ positions,and having hydroxy-protecting groups at the 5, 7, 3′, and 4′ positions.9. The activated, blocked, hydroxy-protected monomer of claim 8, whereinthe monomer is epicatechin.
 10. The activated, blocked,hydroxy-protected monomer of claim 8, wherein the C₂-C₆ alkoxy groupwith the terminal hydroxy group is 2-hydroxyethoxy.
 11. The activated,blocked, hydroxy-protected monomer of claim 8, wherein the blockinggroup(s) are bromo group(s).
 12. The activated, blocked,hydroxy-protected monomer of claim 8, wherein the protecting groups atthe 5, 7, 3′, and 4′ positions are benzyl groups or methyl groups. 13.The blocked, hydroxy-protected eepicatechin monomer of claim 1 or claim2, wherein the monomer is epicatechin and wherein the protecting groupsare benzyl groups.
 14. An activated, blocked, hydroxy-protectedepicatechin or catechin monomer having at the 4 position a C₂-C₆ alkoxygroup with a terminal hydroxy group, having at the 8 position, or at the6 and 8 positions, or at the 6, 8, and 6′ positions halo blockinggroup(s), and having at the 3, 5, 7, 3′, and 4′ positionshydroxy-protecting groups.
 15. The activated, blocked, hydroxy-protectedmonomer of claim 14, wherein the protecting groups at the 5, 7, 3′, and4′ positions are benzyl groups or methyl groups and the protecting groupat the 3 position is a benzyl group or a tert-butyldimethylsilyl group.16. The activated, blocked, hydroxy-protected monomer of claim 8,wherein the monomer is epicatechin; wherein the C₂-C₆ alkoxy group withthe terminal hydroxy group is 2-hydroxyethoxy; wherein the blockinggroup(s) are bromo group(s); and wherein the protecting groups at the 5,7, 3′, and 4′ positions are benzyl groups.
 17. The activated, blocked,hydroxy-protected monomer of claim 14, wherein the monomer isepicatechin; wherein the C₂-C₆ alkoxy group with the terminal hydroxygroup is 2-hydroxyethoxy; wherein the blocking group(s) are bromogroup(s); wherein the protecting groups at the 5, 7, 3′, and 4′positions are benzyl groups; and wherein the protecting group at the 3position is a tert-butyldimethylsilyl group.
 18. The activated, blocked,hydroxy-protected monomer of claim 14, wherein the monomer isepicatechin.
 19. The activated, blocked, hydroxy-protected monomer ofclaim 14, wherein the C₂-C₆ alkoxy group with the terminal hydroxy groupis -hydroxyethoxy.
 20. The activated, blocked, hydroxy-protected monomerof claim 14, wherein the blocking group(s) are bromo group(s).
 21. Theactivated, blocked, hydroxy-protected monomer of claim 14, wherein theprotecting groups at the 5, 7, 3′, and 4′ positions are benzyl groups ormethyl groups and the protecting group at the 3 position is a benzlygroup or a tert-butyldimethylsilyl group.
 22. The activated, blocked,hydroxy-protected monomer of claim 14, wherein the monomer isepicatechin; wherein the C₂-C₆ alkoxy group with the terminal hydroxygroup is 2-hydroxyethoxy; wherein the blocking group(s) are bromogroup(s); and wherein the protecting groups at the 3, 5, 7, 3′, and 4′positions are benzyl groups.